With respect to EPA's assertion that requiring the reporting of trona inputs, as well as outputs, would "improve the quality of the US GHG Inventory," a review of the narrative in the "Draft Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2014" does not support this statement.[6] From Section 4.11 "Soda Ash Production and Consumption:"
Emission estimates from soda ash production have relatively low associated uncertainty levels in that reliable and accurate data sources are available [emphasis added] for the emission factor and activity data. ...
One source of uncertainty is the purity of the trona ore used for manufacturing soda ash. The emission factor used for the estimate assumes the ore is 100 percent pure, and likely overestimates [emphasis added] the emissions from soda ash manufacture ...
The primary source of uncertainty, however, results from the fact that emission from soda ash consumption [emphasis added] are dependent upon the type of processing employed by each end use.
To paraphrase, EPA has stated in the draft 2016 GHG Inventory that the quality of the data associated with soda ash manufacture is good (i.e., has low uncertainty) and that the methodology used to estimate emissions likely overestimates. Further, EPA's draft GHG Inventory notes that the primary sources of uncertainty in the sector occur downstream from the manufacturing sites that would be affected by this rulemaking. From this information, ACC concludes that the proposed changes would not improve the emissions calculations in the GHG Inventory in any material way. Thus, it is our view that the proposed rule would not achieve its stated purposed (improving the GHG Inventory) and does not warrant the imposition of additional regulatory burdens on the soda ash industry.
EPA goes on to state "this action would propose to streamline the reporting of facility-level consumption data from both CEMS and non-CEMS reporters on a more aggregate level." (81 FR 2563) We find this statement inaccurate with respect to non-CEMS reporters, which must calculate emissions using a more complex methodology that relies on many data elements.
In the Final Inputs Rule (79 FR 63750, October 24, 2014), EPA removed four data elements from Subpart CC, one of which was "the monthly consumption of trona or liquid alkaline for each manufacturing line (non-CEMS)." EPA clearly intended to remove data element 98.296(b)(5), as it was one of four data elements listed in "Table 3: Subparts for Which Reporting Elements are Removed." (79 FR 63765) We do not know why this data element was removed, however, because EPA did not provide explanations for removing data elements.
In the proposed rule, EPA advocates reinstating reporting of the "annual consumption of trona or liquid alkaline feedstock at the facility level" for non-CEMs reporters (81 FR 2614). ACC does not find EPA's justification for revising Subpart CC significant enough to merit a reversal in the treatment of this data element, especially given that the previous change was made just 18 months ago. As stated earlier, with the sixth year of GHG reporting completed, it is our view that the number of regulatory changes should be decreasing, not increasing. We further urge EPA to avoid these types of unnecessary reversals in the future.
Footnotes:
(6) U.S. Environmental Protection Agency, Draft Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990  -  2014, EPA 430-R-16-002, February 22, 2016, p. 4-40.
Response: EPA is not finalizing the amendments that would have required reporting of the facility-level annual consumption of trona or liquid alkaline feedstock. See Section III.P.2 of the preamble to the final rule for EPA's response to this comment.
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Commenter Name:  Chris Greissing
Commenter Affiliation:  Industrial Minerals Association-North America (IMA-NA)
Document Control Number:  EPA-HQ-OAR-2015-0526-0068
Comment Excerpt Number:  3
Comment: EPA states in preamble Section II.P that the "addition of this data element [would] help improve the quality of the US GHG Inventory by using aggregated facility level data. These data are already required to be reported on the manufacturing line basis for subpart CC reporters that report using CEMS."
A. Because the majority of soda ash producers are not reporting using CEMS for the large majority of their production lines, the statement appears to be gratuitous with respect to dimensioning the efforts required to comply should the proposal be adopted without change, i.e., it would require additional recordkeeping and reporting efforts by all reporters, as they are all understood to be "non-CEMS reporters."
B. With respect to EPA's assertion that requiring the reporting of trona inputs, as well as outputs, would "improve the quality of the US GHG Inventory," a review of the narrative in the "Draft Inventory of U.S. Greenhouse Gas Emissions and Sinks: 1990-2014" would not support this statement. From Section 4.11 "Soda Ash Production and Consumption:"
Emission estimates from soda ash production have relatively low associated uncertainty levels in that reliable and accurate data sources are available [emphasis added] for the emission factor and activity data. ...
One source of uncertainty is the purity of the trona ore used for manufacturing soda ash. The emission factor used for the estimate assumes the ore is 100 percent pure, and likely overestimates [emphasis added] the emissions from soda ash manufacture....
The primary source of uncertainty, however, results from the fact that emission[s] from soda ash consumption [emphasis added] are dependent upon the type of processing employed by each end use.
To paraphrase, EPA believes the quality of data associated with soda ash manufacture is (1) good, i.e., low uncertainty, (2) likely overestimates emissions, and (3) primary uncertainty occurs downstream from the manufacturing sites that would be affected by this rulemaking. The GHGRP rule, as proposed, would do nothing to address ore quality and the potential for overestimated emissions in the US Greenhouse Gas Inventory, nor would Ms. Carole Cook Docket No. EPA-HQ-OAR-2015-0526 March 30, 2016  -  Page 3 this rule address downstream consumption of soda ash. As such, the proposed rule would not achieve its stated purposed and does not warrant the imposition of additional regulatory burdens on the soda ash industry.
C. Section II.P goes on to state that "this action would propose to streamline the reporting of facility-level consumption data from both CEMS and non-CEMS reporters on a more aggregate level." This statement is inaccurate and misleading. Nothing is streamlined for a non-CEMS reporter  -  quite the opposite. Non-CEMS reports have additional regulatory reporting burdens, which are not necessary to fulfill programmatic requirements.
Response: EPA is not finalizing the amendments that would have required reporting of the facility-level annual consumption of trona or liquid alkaline feedstock. See Section III.P.2 of the preamble to the final rule for EPA's response to this comment.
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Commenter Name:  Chris Greissing
Commenter Affiliation:  Industrial Minerals Association-North America (IMA-NA)
Document Control Number:  EPA-HQ-OAR-2015-0526-0068
Comment Excerpt Number:  4
Comment: The discussion of Subpart CC in the preamble seems to suggest that the rulemaking would enable EPA to "transparently determine national emissions based on trona consumption," however, this statement appears to assume that collecting trona mass inputs from non-CEMS reporters who are not using Equation CC-1 at §98.293 (b)(2) would somehow address the one source of uncertainty noted in the Inventory of U.S. Greenhouse Gas Emissions and Sinks as relevant to producers  -  the purity of the ore, not its mass. Collecting facility-level feedstock mass is a solution in search of a problem. If EPA wished to refine the estimate of trona purity, the USGS is an excellent source of information. The largest uncertainties reside in downstream soda ash use, and are not relevant to producers.
Response: EPA is not finalizing the amendments that would have required reporting of the facility-level annual consumption of trona or liquid alkaline feedstock. See Section III.P.2 of the preamble to the final rule for EPA's response to this comment.
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Commenter Name:  Chris Greissing
Commenter Affiliation:  Industrial Minerals Association-North America (IMA-NA)
Document Control Number:  EPA-HQ-OAR-2015-0526-0068
Comment Excerpt Number:  5
Comment: In the Final Inputs Rule (79 FR 63750, October 24, 2014), EPA removed four data elements from Subpart CC, one of which was "the monthly consumption of trona or liquid alkaline for each manufacturing line (non-CEMS)." Now, in the present rule, EPA is proposing to reinstate reporting of the "annual consumption of trona or liquid alkaline feedstock at the facility level" for non-CEMs reporters (81 FR 2614). EPA's justification does not support a reversal of the previous regulatory determination in the Final Inputs Rule, and soda ash manufacturers should not be subjected to increased regulatory reporting burdens that are of limited value.
Response: EPA is not finalizing the amendments that would have required reporting of the facility-level annual consumption of trona or liquid alkaline feedstock. See Section III.P.2 of the preamble to the final rule for EPA's response to this comment.
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Commenter Name:  Chris Greissing
Commenter Affiliation:  Industrial Minerals Association-North America (IMA-NA)
Document Control Number:  EPA-HQ-OAR-2015-0526-0068
Comment Excerpt Number:  1
Comment: EPA states in GHGRP preamble section II.P, EPA is "proposing two revisions that are intended to improve the quality of data collection under subpart CC....[F]or the reasons described in section II.B of this preamble." Please note that soda ash manufacturing is not discussed in section II.B of the preamble.
Response: Section II.B of the preamble to the proposed rule provided a general discussion of amendments proposed to improve the quality of data collected under Part 98 and improve the U.S. GHG Inventory, and was not intended to be exhaustive.
Regarding the comment on revisions to improve the quality of data collection in subpart CC, see Section III.P.2 of the preamble to the final rule for EPA's response to this comment.
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Commenter Name:  Chris Greissing
Commenter Affiliation:  Industrial Minerals Association-North America (IMA-NA)
Document Control Number:  EPA-HQ-OAR-2015-0526-0068
Comment Excerpt Number:  2
Comment: The two changes would require additional records be reported regarding inputs to each manufacturing line and facility level inputs. The rule already requires reporting of outputs of both soda ash produced and GHG emitted, wholly fulfilling the statutory requirements for the program.
Response: EPA is not finalizing the amendments that would have required reporting of the facility-level annual consumption of trona or liquid alkaline feedstock. See Section III.P.2 of the preamble to the final rule for EPA's response to this comment.
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Revisions to Subpart DD
Improve Quality: Reporting U.S. state, states, or territory in which the electric power system lies
Commenter Name:  Patrick J. Renshaw
Commenter Affiliation:  PPL Electric Utilities Corporation
Document Control Number:  EPA-HQ-OAR-2015-0526-0056
Comment Excerpt Number:  2
Comment: Nor should EPA require us to determine SF6 emissions on a state-specific basis. Rather, the current mass balance equations should continue to be used to calculate total emissions from all of PPL EU's facilities combined. This is particularly appropriate for SF6 which is a pollutant that has global impact rather than local or regional impact.
EPA is proposing to revise 40 C.F.R. § 98.306(m) to require the electric power system reporter to provide the name of the U.S. state, states or territory in which the electric power system lies and the total miles of transmission and distribution lines that lie in each state or territory. EPA is requesting comment on two possible alternatives to report: one would be to report the total transmission and distribution lines that lie in each state or territory within the facility boundary; the other would be to report the emissions from equipment within the facility boundary for each state or territory.
While electric utilities have robust tools in place to track all SF6 equipment on-system and all SF6 gas used/recycled on-system, we do not generally track the exact location of every lb of SF6 gas that is lost on-system. This is why the current systems are setup as a "mass balance" to track all SF6 coming into and out of the system. The delta is "lost gas" across the entire system.
While PPL EU believes that the additional burden of collecting the data proposed by EPA under either option will not provide meaningful information beyond the current mass balance approach, option one would certainly be far less burdensome than trying to quantify SF6 gas loss by state. However, if option one is selected, it will be important to bear in mind that the data collection will not provide a clear way to compare usage or loss by state (if that is the intent) given the tremendous variation in the equipment used on-system (e.g. Gas Insulating Substation "GIS" substation vs. Open Air substation), as well as variations in overall system designs. For example, the size and number of potential SF6 containing equipment needed to support a high demand/high density area like NY City could far exceed the potential SF6 containing equipment needed to support a rural town that would require a far greater number of miles of Transmission and Distribution lines to serve a less dense/lower load population area.
Response: EPA is finalizing the addition of a data element to require the reporter to provide the name of the U.S. state, states, or territory in which the electric power system lies, but is not finalizing the proposed requirement to report the total miles of transmission and distribution lines that lie in each state or to report the total emissions in each state or territory. See Section III.Q.2 of the preamble to the final rule for EPA's response to this comment.
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Improve Quality: Reporting total miles of transmission & distribution lines in each state or territory
Commenter Name:  Debra J. Jezouit and Leslie Couvillion, Baker Botts, L.L.P
Commenter Affiliation:  Class of '85 Regulatory Response Group
Document Control Number:  EPA-HQ-OAR-2015-0526-0070
Comment Excerpt Number:  4
Comment: EPA has not provided data to support its claim that SF6 emissions are correlated with transmission line length. EPA proposes to add new reporting provisions for facilities[15] under 40 C.F.R. § 98.306(m) to require reporters to identify the name of the U.S. state, states, or territory in which the electric power system lies and the total miles of T&D lines that are in each state or territory.[16] EPA claims that these data elements would allow the public to more easily identify the state, states, or territory within which the electric system lies, as well as to compare the miles of T&D lines in each state or territory to the total miles of T&D lines and then approximate the percentage of emissions that occur within each state or territory.[17] EPA further claims that "[a]s discussed in the U.S. GHG Inventory, SF6 emissions from electric power systems are correlated with the length of their transmission lines."[18]
The Group objects to EPA's failure to provide data to support the Proposed Rule's claim that there is a correlation between SF6 emissions and transmission line length. The Group disagrees with this claim because transmission lines do not themselves contain SF6. Instead, this gas is utilized primarily for insulating purposes in substations and switchyards. The Group requests that EPA provide further justification in the final rule to support its claim that there is a correlation between SF6 emissions and transmission line length. If EPA cannot justify this claim, EPA should not require reporting of total miles of T&D lines in each state or territory. This requirement could be burdensome for companies with T&D systems spanning more than one state because these companies may not record this information on a state-by-state or territory-by territory basis. EPA has not adequately justified imposing this potential additional burden on reporters.
Footnotes:
(15) Subpart DD defines a facility as "an electric power system, comprised of all electric [T&D] equipment insulated with or containing [sulfur hexaflouride ("SF6")] or [perfluorocarbon ("PFC")] that is linked through electric power transmission or distribution lines and functions as an integrated unit that is owned, serviced, or maintained by a single electric power transmission or distribution entity (or multiple entities with a common owner), and that is located between: (1) The point(s) at which electric energy is obtained from an electricity generating unit or a different electric power transmission or distribution entity that does not have a common owner; and (2) the point(s) at which any customer or another electric power transmission or distribution entity that does not have a common owner receives the electric energy. The facility also includes servicing inventory for such equipment that contains SF6 or PFC." 81 Fed. Reg. at 2,563.
(16) Id. at 2,563.
(17) Id.
(18) Id.
Response: EPA is not finalizing a requirement to report total miles of transmission and distribution lines in each state or territory. See Section III.Q.2 of the preamble to the final rule for additional information.
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Commenter Name:  Patrick J. Renshaw
Commenter Affiliation:  PPL Electric Utilities Corporation
Document Control Number:  EPA-HQ-OAR-2015-0526-0056
Comment Excerpt Number:  3
Comment: The agency also should not rely on miles of transmission equipment as a proxy for emissions since this does not provide accurate emissions data nor does it allow for an accurate means to "benchmark" one utility against another for SF6 usage.
PPL EU does not believe it would be appropriate to use transmission line miles as a proxy for SF6 use and emissions for the reason stated previously. Therefore, transmission & distribution miles would not be an accurate proxy for SF6 use and emissions across the industry. There is also the question of equipment location as much of the SF6 used on-system is located within substations or switchyards. For examples, a utility in a rural area may choose to build an open air substation where the only SF6 gas used would be in the circuit breakers. This can be done as land is not usually a restricting factor. A similar electrical need being addressed in a congested area might utilize a more expensive, but smaller footprint design, known as a GIS substation. The SF6 usage for this design is far greater than an open air design, but the underlying electrical need and function is the same. Looking simply at line miles does not take these variations into account.
The mass balance process currently available in the EPA's Greenhouse gas reporting program, accounts for all gas on-system and we would recommend no changes to that process.
Response: EPA is not finalizing a requirement to report total miles of transmission and distribution lines in each state or territory. See Section III.Q.2 of the preamble to the final rule for additional information.
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Commenter Name:  Emily Fisher
Commenter Affiliation:  Edison Electric Institute (EEI)
Document Control Number:  EPA-HQ-OAR-2015-0526-0035
Comment Excerpt Number:  10
Comment: EPA requests comment on whether miles of transmission lines alone are likely to be a better predictor of SF6 use and emissions than combined miles of transmission and distribution lines. If so, EPA could simply require reporting of the miles of transmission lines in each state or territory. See id. It would not be appropriate to use transmission lines as a proxy for SF6 use and emissions. While miles of transmission could be a reasonable metric for estimating use and emissions in rural areas, larger cities have far more miles associated with distribution than they do transmission. Accordingly, transmission miles would not be an accurate proxy for SF6 use and emissions across the industry.
Response: EPA is not finalizing a requirement to report total miles of transmission and distribution lines in each state or territory. See Section III.Q.2 of the preamble to the final rule for additional information.
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Commenter Name:  Lauren E. Freeman, Hunton & Williams LLP
Commenter Affiliation:  Utility Air Regulatory Group (UARG)
Document Control Number:  EPA-HQ-OAR-2015-0526-0046
Comment Excerpt Number:  6
Comment: EPA proposes to add new requirements to Subpart DD § 98.306 to require reporting of the total miles of transmission and distribution lines located in each state or territory in which the facility lies. EPA solicits comment on several alternatives. Id. at 2563-64. UARG has a number of concerns with these proposed requirements, which would be overly burdensome and in some cases not useful. Those concerns are consistent with the comments on Subpart DD submitted by the Edison Electric Institute, EPA-HQ-OAR-2015-0526-0035, and UARG supports them.
Response: EPA is not finalizing a requirement to report total miles of transmission and distribution lines in each state or territory. See Section III.Q.2 of the preamble to the final rule for additional information.
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Commenter Name:  Mary Josie Blanchard
Commenter Affiliation:  Office of Environmental Policy and Compliance, Office of the Secretary, U.S. Department of the Interior (DOI)
Document Control Number:  EPA-HQ-OAR-2015-0526-0042
Comment Excerpt Number:  1
Comment: Subpart DD is proposing to require the inclusion of the total miles of transmission and distribution lines that lie in each state; this comparison would not be appropriate for electric generating facilities that do not own or operate transmission or distribution lines. As an example, Reclamation owns and operates hydroelectric generating facilities that do not fall under the reporting requirements of Subpart D, Electricity Generation, but does provide generation interconnections for supplying electricity to transmission and distribution systems. Reclamation requests that the reporting be limited to identifying the state within which the Electric Generation Facility exists. The comparison of miles of transmission and distribution to SF 6 emissions would indicate higher SF6 emissions for Reclamation and other generation providers that only have transmission or distribution lines for generation interconnections, in comparison to transmission or distribution providers with hundreds of miles of lines. Reclamation suggests that the miles of transmission or distribution lines would not be a good indicator of SF6 use.
Response: EPA is not finalizing a requirement to report total miles of transmission and distribution lines in each state or territory. See Section III.Q.2 of the preamble to the final rule for additional information.
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Commenter Name:  Debra J. Jezouit and Leslie Couvillion, Baker Botts, L.L.P
Commenter Affiliation:  Class of '85 Regulatory Response Group
Document Control Number:  EPA-HQ-OAR-2015-0526-0070
Comment Excerpt Number:  9
Comment: Reporting Total T&D Lines versus Emissions versus Transmission Lines Alone. EPA requests comment on (1) whether it would be less burdensome for facilities to report the total T&D lines that lie in each state or territory within the facility boundary or to report the emissions for each state or territory within the facility boundary; and (2) whether miles of transmission lines alone are likely to be a better predictor of SF6 use and emissions than combined miles of T&D lines.[31] While the Group believes that EPA has failed to provide data to support the claim that there is a correlation between SF6 emissions and transmission line length, the Group does not have a strong preference on any of these alternatives and simply requests that EPA clarify in the final rule how this information should be reported.
Footnotes:
(31) 81 Fed. Reg. at 2,563.
Response: EPA is not finalizing a requirement to report total miles of transmission and distribution lines in each state or territory. See Section III.Q.2 of the preamble to the final rule for additional information.
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Commenter Name:  Emily Fisher
Commenter Affiliation:  Edison Electric Institute (EEI)
Document Control Number:  EPA-HQ-OAR-2015-0526-0035
Comment Excerpt Number:  8
Comment: EPA requests comment on whether it would be less burdensome for T&D systems to report the total transmission and distribution lines that lie in each state or territory within the facility boundary or to report the emissions for each state or territory within the
facility boundary. See 40 C.F.R. § 98.306(m). Given that T&D systems likely track emissions and transmission/distribution line miles on a state/territory basis, the two options would be equally burdensome.
Response: EPA is not finalizing a requirement to report total miles of transmission and distribution lines in each state or territory, nor is EPA finalizing the requirement to report the emissions for each state or territory within the facility boundary. See Section III.Q.2 of the preamble to the final rule for additional information.
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Improve Quality: Separate reporting for nameplate capacities of hermetically sealed-pressure equipment and other SF6- and PFC-insulated equipment installed and retired during the year
Commenter Name:  Emily Fisher
Commenter Affiliation:  Edison Electric Institute (EEI)
Document Control Number:  EPA-HQ-OAR-2015-0526-0035
Comment Excerpt Number:  11
Comment: Currently, electric transmission and distribution facilities are required to include the nameplate capacities of new and retiring hermetically sealed-pressure equipment, along with the corresponding quantities for other electrical equipment, in their emission calculations. See id.; see also 40 C.F.R. § 98.303. They are also required to report the total nameplate capacity of new equipment, including hermetically sealed-pressure equipment, and the total nameplate capacity of retiring equipment, including hermetically sealed-pressure equipment. See id. However, they are not required to distinguish between hermetically sealed-pressure and other equipment in these reports. See id.
In lieu of reporting the total nameplate capacity for all hermetically sealed-pressure equipment and other equipment, EPA proposes to require facilities to separately report the nameplate capacities of hermetically sealed-pressure equipment and other equipment that they install and retire during the year. See id. The proposed amendments would add reporting of the nameplate capacities of new hermetically sealed-pressure switchgear (proposed 40 CFR 98.306(a)(2)), new SF6- or PFC-insulated equipment other than hermetically sealed-pressure switchgear (proposed 40 CFR 98.306(a)(3)), retired hermetically sealed-pressure switchgear (proposed 40 CFR 98.306(a)(4)), and retired SF6- or PFC-insulated equipment other than hermetically sealed-pressure switchgear (proposed 40 CFR 98.306(a)(5)).
The Reporting Rule currently does not require reporting of the quantity of SF6 inside each piece of equipment or the number of pieces of SF6-insulated equipment. See id. Instead, the total nameplate capacities of all equipment are aggregated in the mass balance equation used to calculate emissions. See 40 C.F.R. § 98.303. EPA states that disaggregating and reporting this additional data would enable the Agency to better understand the quantities of SF6 contained in hermetically sealed-pressure equipment, but does not state any other purpose for collecting this data. EPA also asserts that these data elements represent information that reporters are expected to have readily available and would therefore generally result in only a slight increase in reporting burden. See id.
As a preliminary matter, contrary to EPA's assertions, not all T&D system owners and operators typically record whether a particular piece of equipment is hermetically sealed, either when it is purchased or when it is retired. Collecting this data would require reporters to reconfigure supply chain tracking so that EPA could gather information on a relatively small amount of equipment. This would represent more than a slight increase in the reporting burden. EPA has not demonstrated that this increased burden on reporters is necessary in light of the limited value of the information it would provide EPA.
Response: EPA is finalizing the proposed separate reporting of the number of and the nameplate capacities of hermetically sealed-pressure equipment and other equipment that is installed and retired during the year. See Section III.Q.2 of the preamble to the final rule for EPA's response to this comment.
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Commenter Name:  Patrick J. Renshaw
Commenter Affiliation:  PPL Electric Utilities Corporation
Document Control Number:  EPA-HQ-OAR-2015-0526-0056
Comment Excerpt Number:  1
Comment: PPL EU believes the EPA should not require owners and operators of electrical transmission and distribution systems to separately catalogue and report the name plate capacities of smaller hermetically sealed equipment that is part of a larger piece of equipment.
EPA proposes to add reporting elements to subpart DD related to the nameplate capacities and numbers of pieces of new and retiring equipment. Under EPA's proposed amendment, the nameplate capacities of all newly installed and retired equipment, including hermetically sealed equipment contained within larger pieces of equipment, would need to be reported individually. EPA states the purpose of this information is to provide them with a better understanding of the quantity of SF6 gas contained in hermetically sealed-pressure equipment. However, EPA does not explain why it is important to understand the quantity of SF6 gas in hermetically-sealed equipment, particularly where the hermetically- sealed equipment is a component of a larger piece of equipment as to which the total SF6 gas is included under the current mass balance approach. In addition, even if there is value in understanding the quantity of SF6 gas in individual hermetically-sealed equipment, this does not justify EPA's proposal to require nameplate capacity information on every new and retired piece of equipment.
EPA apparently assumes that detailed records as proposed by EPA are readily available; however in general owners and operators of electric transmission and distribution systems are not provided with the individual nameplate capacities of hermetically sealed equipment that are components of larger equipment. Rather, the manufacturer or supplier will provide only the total nameplate capacity (including all components) of the larger equipment. Collecting data on individual components of larger equipment would require manufacturers and suppliers to provide a breakdown of the SF6 quantities in each component of the equipment and would require PPL to develop a new database tracking system and new processes for capturing the information and reporting it to EPA.
The burden imposed on industry to individually track nameplate capacity with respect to each hermetically-sealed component of a larger piece of equipment is not outweighed by any discernable benefit, as the hermetically-sealed components are not individually maintained. If such a component fails, the entire piece of equipment would be scrapped and any difference in weight of the equipment would be included in the SF6 emissions reported under the current mass balance approach.
Response: EPA is finalizing the proposed separate reporting of the number of and the nameplate capacities of hermetically sealed-pressure equipment and other equipment that is installed and retired during the year. See Section III.Q.2 of the preamble to the final rule for EPA's response to this comment.
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Commenter Name:  Debra J. Jezouit and Leslie Couvillion, Baker Botts, L.L.P
Commenter Affiliation:  Class of '85 Regulatory Response Group
Document Control Number:  EPA-HQ-OAR-2015-0526-0070
Comment Excerpt Number:  5
Comment: EPA would require facilities to (1) separately report the nameplate capacities of hermetically sealed-pressure equipment and other equipment that they install and retire during the year;20 and (2) report the numbers of pieces of hermetically sealed-pressure equipment and other equipment that they install and retire during the year.[21] EPA believes these additional requirements "represent information that reporters are expected to have readily available and would therefore generally result in only a slight increase in reporting burden."[22]
The Class of '85 objects to EPA's failure to provide a basis for requiring segregated reporting of hermetically sealed-pressure equipment. As EPA has acknowledged, hermetically sealed-pressure equipment is a de minimis source of SF6 emissions due to the equipment's small physical size and low maintenance requirements.[23] EPA further states that "historically, hermetically sealed-pressure equipment has been considered to be a relatively small source of SF6 emissions in the U.S., but its importance is known to be growing internationally and may also be growing domestically."[24] EPA has not provided clear evidence in the Proposed Rule for how hermetically sealed-pressure equipment has increased in significance as a source of SF6 emissions in recent years. EPA should not create potentially burdensome requirements for facilities based on what "may" be occurring in the nation.
Footnotes:
(20) The proposed amendments would require reporting of nameplate capacities of (i) new hermetically sealed-pressure switchgear during the year; (ii) new SF6 or PFC-insulated equipment other than hermetically sealed-pressure switchgear; (iii) retired hermetically sealed-pressure switchgear; and (iv) retired SF6 or PFC-insulated equipment other than hermetically sealed-pressure switchgear. 81 Fed. Reg. at 2,564.
(21) Id.
(22) Id.
(23) Indeed, EPA previously excluded hermetically sealed-pressure equipment from the requirement to annually inventory the total nameplate capacity of a facility's electrical equipment because "hermetically sealed-pressure equipment tends to have small individual charge sizes, to be serviced only rarely or not at all, and to be spread in large numbers throughout [T&D] networks, making it relatively difficult to track after it is installed." Id. at n. 19.
(24) Id. at 2,564.
Response: EPA is finalizing the proposed separate reporting of the number of and the nameplate capacities of hermetically sealed-pressure equipment and other equipment that is installed and retired during the year. See Section III.Q.2 of the preamble to the final rule for EPA's response to this comment.
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Commenter Name:  Lauren E. Freeman, Hunton & Williams LLP
Commenter Affiliation:  Utility Air Regulatory Group (UARG)
Document Control Number:  EPA-HQ-OAR-2015-0526-0046
Comment Excerpt Number:  7
Comment: EPA proposes to add new requirements to Subpart DD § 98.306 to require reporting of the nameplate capacities of hermetically sealed and other equipment separately. EPA solicits comment on several alternatives. Id. at 2563-64. UARG has a number of concerns with these proposed requirements, which would be overly burdensome and in some cases not useful. Those concerns are consistent with the comments on Subpart DD submitted by the Edison Electric Institute, EPA-HQ-OAR-2015-0526-0035, and UARG supports them.
Response: EPA is finalizing the proposed separate reporting of the nameplate capacities of hermetically sealed-pressure equipment and other equipment that is installed and retired during the year. See Section III.Q.2 of the preamble to the final rule for EPA's response to this comment.
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Improve Quality: Separate reporting for number of pieces of hermetically sealed-pressured equipment and other SF6- and PFC-insulated equipment installed and retired during the year
Commenter Name:  Emily Fisher
Commenter Affiliation:  Edison Electric Institute (EEI)
Document Control Number:  EPA-HQ-OAR-2015-0526-0035
Comment Excerpt Number:  13
Comment: The Reporting Rule currently does not require reporting of the quantity of SF6 inside each piece of equipment or the number of pieces of SF6-insulated equipment. See id. Instead, the total nameplate capacities of all equipment are aggregated in the mass balance equation used to calculate emissions. See 40 C.F.R. § 98.303. EPA states that disaggregating and reporting this additional data would enable the Agency to better understand the quantities of SF6 contained in hermetically sealed-pressure equipment, but does not state any other purpose for collecting this data. EPA also asserts that these data elements represent information that reporters are expected to have readily available and would therefore generally result in only a slight increase in reporting burden. See id.
Contrary to EPA's assertions, not all T&D system owners and operators typically record whether a particular piece of equipment is hermetically sealed, either when it is purchased or when it is retired. Collecting this data would require reporters to reconfigure supply chain tracking so that EPA could gather information on a relatively small amount of equipment. This would represent more than a slight increase in the reporting burden. EPA has not demonstrated that this increased burden on reporters is necessary in light of the limited value of the information it would provide EPA.
Response: EPA is finalizing the proposed separate reporting of the number of and the nameplate capacities of hermetically sealed-pressure equipment and other equipment that is installed and retired during the year. See Section III.Q.2 of the preamble to the final rule for EPA's response to this comment.
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Commenter Name:  Lauren E. Freeman, Hunton & Williams LLP
Commenter Affiliation:  Utility Air Regulatory Group (UARG)
Document Control Number:  EPA-HQ-OAR-2015-0526-0046
Comment Excerpt Number:  8
Comment: EPA proposes to add new requirements to Subpart DD § 98.306 to require reporting of the numbers of each piece of new and each piece of retired equipment containing sulfur hexafluoride (SF6) or perfluorocarbons (PFC). EPA solicits comment on several alternatives. Id. at 2563-64. UARG has a number of concerns with these proposed requirements, which would be overly burdensome and in some cases not useful. Those concerns are consistent with the comments on Subpart DD submitted by the Edison Electric Institute, EPA-HQ-OAR-2015-0526-0035, and UARG supports them.
Response: EPA is finalizing the proposed separate reporting of the number of pieces of hermetically sealed-pressure equipment and other equipment that is installed and retired during the year. See Section III.Q.2 of the preamble to the final rule for EPA's response to this comment.
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Improve Quality: Alternative approach to report number of pieces of each type of equipment installed or retired by nameplate capacity range
Commenter Name:  Debra J. Jezouit and Leslie Couvillion, Baker Botts, L.L.P
Commenter Affiliation:  Class of '85 Regulatory Response Group
Document Control Number:  EPA-HQ-OAR-2015-0526-0070
Comment Excerpt Number:  7
Comment: EPA has not provided an adequate rationale for the alternative approach of requiring reporting of numbers of pieces of equipment falling under nameplate capacity ranges. As an alternative to requiring the reporting of the total numbers of pieces of (newly installed or retired) hermetically sealed-pressure equipment and other types of equipment, EPA is requesting comment on an alternative approach that would require facilities to report the numbers of pieces of each type of equipment falling into particular nameplate capacity ranges.[26] This alternative approach would be more burdensome because reporting equipment counts based on nameplate capacity ranges requires reporting of more data points than reporting total equipment counts. Reporters would not only need to know the nameplate capacity for each piece of equipment but would then have to sort the data into several different "bins."[27] EPA recognizes that "this approach would require more effort [for reporters] than providing the total numbers of pieces of equipment newly installed and retired for hermetically sealed-pressure equipment and for all other equipment."[28] In light of this increased burden, the Group sees little benefit to this approach nor does EPA provide one. As long as reporters provide the required equipment counts, EPA should be able to assemble the data into whatever "bin ranges" EPA feels are necessary after receiving the reports. If EPA does finalize the proposal to require segregated reporting of numbers of pieces of different types of equipment, EPA should only require reporting of total equipment counts and not equipment counts falling into particular nameplate capacity ranges. Alternatively, EPA should allow facilities to choose between the two approaches that EPA has proposed⎯reporting total equipment counts or equipment counts sorted into nameplate capacity ranges.
Footnotes:
(26) 81 Fed. Reg. at 2,564.
(27) EPA offers one possible set of nameplate capacity ranges, consisting of seven different range "bins." See id., Table 6. If EPA were to finalize this hypothetical set of nameplate capacity ranges, it appears that reporters would have to submit 28 different equipment count figures to EPA (i.e., 14 figures indicating the numbers of both new and retired pieces of hermetically sealed-pressure equipment falling into each of the seven nameplate capacity range "bins" and 14 figures indicating the numbers of both new and retired pieces of other types of equipment falling into each of the seven nameplate capacity range "bins").
(28) Id. at 2,564.
Response: EPA is finalizing the proposed separate reporting of the number of and the nameplate capacities of hermetically sealed-pressure equipment and other equipment that is installed and retired during the year. We are not requiring facilities to further segregate equipment counts and nameplate capacities into nameplate capacity ranges.
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Commenter Name:  Emily Fisher
Commenter Affiliation:  Edison Electric Institute (EEI)
Document Control Number:  EPA-HQ-OAR-2015-0526-0035
Comment Excerpt Number:  15
Comment: EPA requests comment on an alternative approach in which facilities would report the numbers of pieces of each type of equipment that are newly installed or retired and that fall into particular nameplate capacity ranges. See id. EPA should not require separate reporting of nameplate capacities for individual pieces of equipment or reporting based on the range of charge sizes. Distribution systems across the industry track a significant amount of equipment that contains anywhere from 0.6 lb of SF6 to 25 lb of SF6, with a very large percentage in the lower end of that range. Because tracking and reporting is internally managed across the industry, modifying databases to report total pieces of each type of equipment in specified capacity ranges would prove very burdensome. As EPA has not specified a purpose for the collection of this data, there is no justification for increasing the reporting burden on T&D system owners and operators.
Response: EPA is finalizing the proposed separate reporting of the number of and the nameplate capacities of hermetically sealed-pressure equipment and other equipment that is installed and retired during the year. We are not requiring facilities to further segregate equipment counts and nameplate capacities into nameplate capacity ranges.
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Commenter Name:  Patrick J. Renshaw
Commenter Affiliation:  PPL Electric Utilities Corporation
Document Control Number:  EPA-HQ-OAR-2015-0526-0056
Comment Excerpt Number:  5
Comment: PPL EU believes that EPA should not require separate reporting of nameplate capacities for individual pieces of equipment or reporting based on the range of charge sizes. Transmission and Distribution systems across the industry track a significant amount of equipment that contains anywhere from 0.6 lb of SF6 to over 1,000 lbs. of SF6, with a very large percentage in the lower end of that range. Absent a clearly articulated reason for imposing the increased reporting burden on transmission and distribution system owners and operators as proposed by EPA, PPL recommends the continued use of the mass balance system now in place.
Response: EPA is finalizing the proposed separate reporting of the number of and the nameplate capacities of hermetically sealed-pressure equipment and other equipment that is installed and retired during the year. We are not requiring facilities to further segregate equipment counts and nameplate capacities into nameplate capacity ranges.
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Comments on Subpart DD Issues not proposed
Commenter Name:  Mary Josie Blanchard
Commenter Affiliation:  Office of Environmental Policy and Compliance, Office of the Secretary, U.S. Department of the Interior (DOI)
Document Control Number:  EPA-HQ-OAR-2015-0526-0042
Comment Excerpt Number:  2
Comment: We request that the definition of hermetically sealed-pressure equipment be better defined under the definitions in Subpart DD (Proposed 40 CFR 98.306 (a)). Hermetically sealed-pressure equipment is defined as air tight by many sources. All SF 6 containing equipment is essentially airtight, but has the means to add or remove gas. Reclamation recognizes that hermetically sealed-pressure is to indicate equipment that does not have the ability to be maintained, or allows the addition or removal of SF6 as explained in footnote 19 on page 2564 of Federal Register Vol. 81 No. 10. Since the footnote indicates that hermetically sealed equipment might be serviceable, it is unclear exactly what equipment would fall under this definition. Reclamation requests if hermetically sealed-pressure strictly pertains to equipment where the SF6 charge cannot be evacuated from the equipment prior to disposal, then the definition needs to reflect that accordingly.
Response: EPA does not agree that "hermetically sealed" must be defined for the purposes of these additional reporting requirements. See Section III.Q.2 of the preamble to the final rule for EPA's response to this comment.
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Commenter Name:  Debra J. Jezouit and Leslie Couvillion, Baker Botts, L.L.P
Commenter Affiliation:  Class of '85 Regulatory Response Group
Document Control Number:  EPA-HQ-OAR-2015-0526-0070
Comment Excerpt Number:  11
Comment: Defining "Hermetically Sealed-Pressure Switchgear" Equipment. EPA does not provide a definition of "hermetically sealed-pressure switchgear" equipment under Subpart DD in the Proposed Rule. The Group requests that EPA clearly define "hermetically sealed-pressure switchgear" equipment in the final rule. The Group believes that "hermetically sealed-pressure switchgear" equipment should be defined in terms of equipment that is "non-maintainable" (i.e., that has no valves or ports to add or maintain the SF6 within the equipment).
Response: EPA does not agree that "hermetically sealed-pressure switchgear" must be defined for the purposes of the final rule. See Section III.Q.2 of the preamble to the final rule for EPA's response to this comment.
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Commenter Name:  Emily Fisher
Commenter Affiliation:  Edison Electric Institute (EEI)
Document Control Number:  EPA-HQ-OAR-2015-0526-0035
Comment Excerpt Number:  14
Comment: EPA has not provided a definition of "hermetically sealed." Such definition has not been necessary in the past, but would be needed if EPA determines that it is appropriate to require T&D owners and operators to differentiate between hermetically sealed and other equipment in subpart DD reports.
Response: EPA does not agree that "hermetically sealed-pressure switchgear" must be defined for the purposes of the final rule. See Section III.Q.2 of the preamble to the final rule for EPA's response to this comment.
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Commenter Name:  Patrick J. Renshaw
Commenter Affiliation:  PPL Electric Utilities Corporation
Document Control Number:  EPA-HQ-OAR-2015-0526-0056
Comment Excerpt Number:  4
Comment: EPA currently has not defined hermetically sealed. If the proposed rule changes are adopted, it will be critical for transmission and distribution operators to fully understand and identify what is hermetically sealed equipment.
Response: EPA does not agree that "hermetically sealed-pressure switchgear" must be defined for the purposes of the final rule. See Section III.Q.2 of the preamble to the final rule for EPA's response to this comment.
Revisions to Subpart FF
Streamlining: Revisions to 40 CFR 98.2(i)(3) to clarify when abandoned underground mines may cease reporting
Commenter Name:  Bruce Watzman
Commenter Affiliation:  National Mining Association (NMA)
Document Control Number:  EPA-HQ-OAR-2015-0526-0051
Comment Excerpt Number:  6
Comment: Exclusion for abandoned mines. We appreciate and support the agency's proposal to exclude reporting for mines that have been abandoned and sealed. Unfortunately, the reliance on MSHA determinations is problematic as MSHA determinations are often not accurate nor timely. EPA is correct that, "MSHA regulations require operators to seal any mine that has been permanently closed or abandoned for more than 90 days."[5] This regulation notwithstanding, MSHA inspection protocols and updating of the Mine Data Retrieval System often result in an extended period of time before public knowledge of an abandonment is recorded. EPA needs to be cognizant of this to avoid underground coal mine operators being held responsible for reporting emissions where none occur or being found non-compliant with the reporting requirements.
Footnotes:
(5) 80 Fed. Reg. 2565 (Jan. 15, 2016)
Response: EPA is finalizing revisions to enable underground coal mines that have ceased operations and have been abandoned and sealed to cease reporting to the GHGRP per the provisions of 40 CFR 98.2(i)(3), but has removed the proposed requirement that relied on the MSHA determination of the mine's operational status as "abandoned." See Section III.R.2 of the preamble to the final rule for EPA's response to this comment.
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Commenter Name:  Bill Bissett
Commenter Affiliation:  Kentucky Coal Association
Document Control Number:  EPA-HQ-OAR-2015-0526-0072
Comment Excerpt Number:  5
Comment: KCA generally supports EPA's decision to exclude abandoned and sealed mines from reporting requirements. However, KCA disagrees with reliance on the MSHA Mine Data Retrieval System to determine whether a mine has been abandoned. MSHA inspection protocols and administrative delays in updating the Mine Data Retrieval System could result in a situation where a mine is not listed on the electronic system as abandoned when it has in fact been abandoned and sealed. This could result in uncertainty as to whether reports are required under the GHG Reporting Rule during this lag time. KCA suggests that operators be permitted to simply report the status of the mine in their GHG emission reports required by the existing Reporting Rule. EPA routinely relies on self-reporting in the enforcement of the programs it administers, and there is no reason why it would not be sufficient for GHG Reporting Rule purposes.
Response: EPA is finalizing revisions to enable underground coal mines that have ceased operations and have been abandoned and sealed to cease reporting to the GHGRP per the provisions of 40 CFR 98.2(i)(3), but has removed the proposed requirement that relied on the MSHA determination of the mine's operational status as "abandoned." See Section III.R.2 of the preamble to the final rule for EPA's response to this comment.
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Improve Quality: Removal of option to use MSHA quarterly inspection reports for CH4 liberated from ventilation systems (40 CFR 98.324(b)(2))
Commenter Name:  Laura M. Goldfarb, Counsel, Steptoe & Johnson
Commenter Affiliation:  Arcelor Mittal Princeton
Document Control Number:  EPA-HQ-OAR-2015-0526-0061
Comment Excerpt Number:  4
Comment: MSHA inspection data should still be allowed for operators who can demonstrate that they meet minimum data quality objectives.
EPA's proposed methodological changes to 40 CFR 98 include provisions to "to amend 40 CFR 98.324(b) to no longer allow MSHA quarterly inspection reports to be used as a source of data for monitoring methane liberated from ventilation systems" and, instead, require the use of either CEMS or independently collected grab samples. In addition, EPA is proposing to add annual coal production to the list of data reporting requirements outlined in 40 CFR 98.326. Finally, EPA seeks comment on "increasing the frequency with which grab samples must be taken, from quarterly to monthly."
EPA notes (page 2566) that it has "determined, through several reporting cycles and a review of MSHA quarterly inspection reports for 30 of the highest emitting mines, that the quarterly flow rate data gathered by MSHA cannot reliably be used for GHG reporting purposes," the technical support being that "MSHA regulations and inspections are intended to ensure mine worker health and safety rather than to quantify specific mine operating parameters." Nonetheless, EPA admits that "MSHA inspections provide important data for assessing mine safety, and If complete, MSHA data may provide a reasonable estimate of methane emissions from underground coal mines." (Emphasis supplied). Despite that acknowledgment, rather than allowing reporters to demonstrate the validity of the MSHA data for their mines, EPA is proposing to prohibit use of that data, regardless of whether it can be validated.
EPA, by its own admission, has focused its data analysis on only 30 of the highest emitting mines. Operators of substantially lower emitting mines are negatively prejudiced by the EPA analysis. The fact is that methane is evolved from the coal seam and the amount liberated may have little relationship to coal production. ArcelorMittal believes that there is no technical evidence to support EPA's conclusions about the lack of a relationship between MSHA data and mines such as the ones not included in the EPA analysis.
The wholesale prohibition of use of MSHA data is arbitrary and fails to provide reporters the flexibility of validating their MSHA data and subsequent continued use of that data. EPA has developed a wealth of information on MSHA data quality. MSHA data is available at no or minimal cost to reporters. Requiring reporters to collect additional data will increase cost substantially without providing a significant environmental benefit. ArcelorMittal urges EPA to allow reporters to propose, for EPA approval, mechanisms by which their site specific data can be demonstrated to meet a baseline quality criterion for 40 CFR Part 98
reporting purposes. Such a process would result in significant efficiencies in data collection and use, and eliminate the possible burdensome redundant collection of data by operators.
Response: EPA is retaining MSHA quarterly data as an acceptable ventilation monitoring method under 40 CFR 98.324(b), with an additional requirement that the mine submit with its annual GHGRP report the MSHA quarterly reports it used to prepare its annual subpart FF report. See Section III.R.2 of the preamble to the final rule for EPA's response to this comment.
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Commenter Name:  Bruce Watzman
Commenter Affiliation:  National Mining Association (NMA)
Document Control Number:  EPA-HQ-OAR-2015-0526-0051
Comment Excerpt Number:  3
Comment: 40 C.F.R. 98.324(b)(1) thru (3)  -  Monitoring and QA/QC Requirements: The premise for these revisions is the agency's view that there are too many gaps in the data and therefore the information reported represents "considerable uncertainty to the calculation of the facility." It is true that measuring gas emissions in an underground coal mine is variable and this variability can impact the results. However, eliminating certain sensible procedures and processes as methods for complying with the reporting obligation does not necessarily solve the problem. In fact, changing the rules of compliance in this case will not ensure more accurate information. New procedures that are not implemented correctly will also result in an outcome that the agency seeks to avoid.
Rather than removing reasonable and tested practices, like the current practice of allowing mine operators to use Mine Safety and Health Administration (MSHA) samples, the agency should consider developing a standard monitoring guideline to address consistency and data quality concerns. Specifically, a guidance document would afford the agency the opportunity to articulate the specific concerns the agency has with "locations and using MSHA samples," while also maintaining an important and cost-effective compliance tool for companies that rely on MSHA's samples.
All in all, we believe EPA and GHG reporters would benefit more from a guidance document on monitoring, rather than changing the rule because a "few" were doing it incorrectly, particularly since the proposed rule would have significant financial ramifications for reporters. We strongly urge EPA to pursue recommend a guidance document in lieu of a new rule to improve sampling quality and consistency of data.
Response: With respect to the comment regarding MSHA quarterly data, the EPA is retaining MSHA quarterly data as an acceptable ventilation monitoring method under 40 CFR 98.324(b) with the additional requirement that the mine submit with its annual GHGRP report the MSHA quarterly reports it used to prepare its annual subpart FF report (see Section III.R.2 of the preamble for additional information). The commenter has also recommended the development of guidance to assist reporters with correctly interpreting MSHA quarterly monitoring reports for subpart FF reporting. The EPA has previously developed a free, publicly available guidance document for this purpose. The document is entitled "Technical Guidance on Using Mine Ventilation Data from the Mine Safety and Health Administration (MSHA) to report Quarterly Methane Emissions from Mine Ventilation Systems." The guidance document is available at https://www.epa.gov/sites/production/files/2015-08/documents/tech_guidance_mine_vent_data.pdf.
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Commenter Name:  Bill Bissett
Commenter Affiliation:  Kentucky Coal Association
Document Control Number:  EPA-HQ-OAR-2015-0526-0072
Comment Excerpt Number:  6
Comment: EPA Should Retain the Existing Approach That Allows Use of MSHA Reported Data.
Given the lack of benefit and considerable increased costs posed by the Proposed Rule, KCA strongly encourages EPA to retain the existing approach to GHG emission reporting. While KCA acknowledges that there is some variability inherent in the MSHA data, that variability does not have any significant effect in the overall assessment of GHG emissions for the nation as a whole. Coal operators are experienced with the methodology required by MSHA monitoring, and can continue to improve the accuracy of the reported data as more experience is obtained. If EPA is concerned that this data is too variable, EPA could take into account the variability that has been documented in calculating ranges of potential GHG emissions in formulating any policies related to underground coal mine GHG emissions.
The fact that some MSHA inspectors or coal mine operators could improve sampling practices under the current regime is only a reason to improve that existing monitoring program. It is not a sound justification for throwing that program out and starting over with a new and more costly methodology. A better, more cost-efficient solution is to provide guidance and training to the industry in the use of existing sampling methodology, rather than "starting from scratch" and hoping for better results.
Response: See response to comment EPA-HQ-OAR-2015-0526-0051, Excerpt 3.
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Improve Quality: Alternative methods for measuring CH4 liberated from ventilation systems (e.g., surface level samples at the fan mouth)
Commenter Name:  Bruce Watzman
Commenter Affiliation:  National Mining Association (NMA)
Document Control Number:  EPA-HQ-OAR-2015-0526-0051
Comment Excerpt Number:  4
Comment: Location of sampling is strongly driven by the following criteria: (1) where best to capture the most air reporting to an exhaust or bleeder fan; (2) where does the most consistency of air flow exist with a tolerable amount of turbulence; and (3) the safety of the individuals conducting the monitoring. Standing at the bottom of the shaft or "in the tube" is too dangerous from a safety perspective and could result in injury to the personnel due to falling objects (i.e. equipment, rock, ice, excessive turbulence and noise). Gathering the sample at the approach provides less turbulence and greater consistency of air flow with no additional risk to personnel. Therefore, NMA supports monitoring within the approach area for best representative results.
Alternatively, NMA encourages EPA to provide mine operator's the option to move the point of data collection (sampling) to the surface. Specifically, we would recommend sampling at the exhaust fan or ventilation point. Some underground operations have observed data that overstates GHG reporting by 23 -37 percent and in some cases as high as 50 percent when comparing MSHA data (collected UG) to surface data. EPA's 2010 Reporting Rule did not provide the option of collecting data at the surface. It is generally understood that variability (i.e., barometric pressure changes, changes in mine plans, etc.) in the ever changing or "dynamic" environment of an underground coal mine cannot be eliminated. However, the use of surface monitoring points should eliminate some potential sources of variability and thus enhance reporting consistency.
Response: EPA agrees that taking samples in the approaches is safer than attempting to take samples at the base of the upcast shaft. In the proposal, EPA sought comment on whether alternatives, such as surface level samples taken at the fan mouth, would achieve the same objective, i.e., improved data quality from mine ventilation systems. EPA encouraged commenters to submit studies, data, and background information that can support additional analysis. EPA appreciates that the commenter has responded to this request by recommending sampling at the exhaust fan or ventilation point at the surface. However, any decision to allow alternative methods such as surface sampling must be supported by data that attest to the accuracy of such a sampling method. Unfortunately, EPA is not in possession of such data for surface sampling, nor did the commenter submit data to support the recommendation. Therefore, EPA is not finalizing any alternative sampling locations in this final rule and is making no changes to the rule in this regard. In the future, EPA would welcome studies or other information that present thorough and unbiased analyses of alternative monitoring methods for possible consideration in future rulemakings.
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Commenter Name:  Bill Bissett
Commenter Affiliation:  Kentucky Coal Association
Document Control Number:  EPA-HQ-OAR-2015-0526-0072
Comment Excerpt Number:  3
Comment: Safety Concerns and Sampling Locations. KCA strongly rejects the suggestion that GHG emissions should be monitored at the bottom of shafts or inside the shafts. Such sampling locations create significant safety concerns and it does not appear that these have been adequately considered. The safety of our miners is of paramount concern, and it should not be jeopardized for any purpose. Monitoring at the approach area will allow for representative samples without creating safety concerns. Allowing the continued use of the data already collected to comply with MSHA requirements creates no safety concerns at all. And as set forth below and above, this MSHA data is more than sufficient for any reasonable monitoring of underground coal mine GHG emissions. A reporting requirement that could endanger the safety of coal miners should not be considered, particularly where an adequate program is already in existence.
One potential approach that EPA did not propose, but that should be considered, is providing the option to sample GHG emissions at the surface. Sampling at a consistent location on the surface creates none of the safety issues posed by other potential sampling locations in the proposed rule. It should also remove variability in sampling results, which is the stated goal of the proposed Subpart FF revisions. Ultimately, it is impossible to eliminate all variability in the dynamic environment of an underground coal mine, emissions from which will always be heavily influenced by issues like changes in barometric pressure and mining plans. However, a consistent surface monitoring point would provide consistency in results. For some operators, it would also alleviate some of the considerable economic burden imposed by the rule.
Response: See response to comment EPA-HQ-OAR-2015-0526-0051, Excerpt 4.
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Improve Quality: Increasing sampling frequency from quarterly to monthly
Commenter Name:  Bruce Watzman
Commenter Affiliation:  National Mining Association (NMA)
Document Control Number:  EPA-HQ-OAR-2015-0526-0051
Comment Excerpt Number:  2
Comment: In general, the proposed revisions to subpart FF do not reflect the big picture which is the overall limited role underground coal mines play in relation to total greenhouse gas (GHG) emissions. According to the agency, GHG emissions for 2014 totaled 3.2 billion metric tons' carbon dioxide equivalent (CO2-e) of which underground coal mines reported 43.2 million metric tons CO2e emissions representing 1.3 percent of the overall emissions. Simply put, the underground coal sector pales in comparison to the other significant GHG emitters yet the agency's proposal will impose approximately 94 percent of the first year costs and 97 percent of the subsequent year's costs on underground coal mines  -  this despite the fact that the proposed rule impacts 30 industry sectors.
For reporting year (RY) 2014, over 8,000 facilities and suppliers reported to the greenhouse gas reporting program.[1] Among these reporters:
8,080 facilities in nine industry sectors reported direct emissions;
direct emissions totaled 3.20 billion metric tons (CO2-e), or about half of total U.S.GHG emissions;
957 suppliers reported; and
92 facilities reported injecting CO2 underground.
 Underground Coal Mines -- Greenhouse Gas Emissions Reported to the GHGRP (all emission values presented in million metric tons CO2e)

                                     2011
                                     2012
                                     2013
                                     2014
Number of Facilities
                                      114
                                      115
                                      126
                                      128
Total emissions (CO2e)
                                     40.3
                                     38.0
                                     40.1
                                     43.2
Emissions by greenhouse gas (CO2e)
 Carbon dioxide (CO2)
 Methane (CH4)
 Nitrous Oxide (N2O)
                                      0.3
                                     40.0
                                      **
                                      0.2
                                     37.8
                                      **
                                      0.2
                                     39.9
                                      **
                                      0.5
                                     42.7
                                      **
**Total reported emissions are less than 0.05 million metric tons CO2e.
Data Source: http://www.epa.gov/ghgreporting/ghgrp-2014-underground-coal-mines
Underground coal mining falls within the "Other Sectors" category, and when you combine all the industries that are small contributors into this category, it represents 142.4 million metric tons CO2e or 4.4 percent of the overall CO2e emissions of 3.2 billion metric tons of CO2e. This is an insignificant proportion of overall emissions. It makes little sense to burden an industry with an increase cost of the over 300 percent to accommodate "improved consistency" when there are other more reasonable approaches.
For example, one approach would be to utilize the knowledge of variances based on the VAM studies at three underground mines.[2] This data permits the calculation of ranges for the underground coal industry and will, given the insignificant contribution in comparison to total releases, eliminate the financial burden that the proposed rule will impose on the industry. We encourage EPA, to adopt this common sense approach rather than impose on the industry another financial burden of limited value.
Should EPA decide to proceed with this rulemaking we encourage the agency to consider its own Data Quality Objectives Process (DQO) developed to "ensure quality assurance (QA) requirements for Agency environmental data collection activities."[3] The DQO process is a series of logical steps and a decision-making tool that guides agencies and the regulated community to understand how large a dataset is needed to answer a specific environmental management question or questions.
DQO provides a measuring tool to determine if data variability, a concern upon which the revisions to Subpart FF are premised, will improve the quality of the decision. Step 1 is to know what question you are trying to answer. Simply assuming "more data granularity would be better" is not a question that needs answering. A question such as "how many data points (samples) from a given data population do I need in order to understand, within a XX percent confidence interval, the total emissions of methane from any given underground mine, considering also such external factors in the population as regionality, production changes, pressure effects, etc." would be more appropriate. First understanding the question one is trying to answer, and why, and the degree of certainty needed around that answer, is the absolute first step. EPA has not demonstrated that this "need for increased granularity" is answering a specific question. We contend the draft rule is simply serving a "feel good" instinct for more data that has no basis in science or environmental statistics.
In the absence of a clear question and a statistical basis we see no justifiable purpose for requiring increased sampling frequency from what is currently required. As EPA's own guidance states, "Use of the DQO Process leads to efficient and effective expenditure of resources; consensus on the type, quality, and quantity of data needed to meet the project goal..."[4] EPA needs a stated "project goal" for this additional data collection requirement. We have serious doubts that the proposed revisions will provide substantially improved knowledge of the total emissions of methane from underground mines, especially when considering the immaterial contribution of GHGs from the UG coal mining sector relative to all other regulated sectors. The currently stated objective does not justify the increased requirements, and EPA has put forth no effort to statistically justify the need for additional data density in these terms. Bottom line...as EPA itself acknowledges, any additional data, of specific types and quality, must be justified based on the question needing answered. This proposed rule fails that fundamental premise.
Footnotes:
(1) http://www.epa.gov/ghgreporting/ghgrp-2014-reported-data
(2) Ruby Canyon Engineering "Evaluation Possible VAM Emissions Estimation Errors Based On Different Sampling Intervals (Quarterly, Monthly, Weekly)": June 10, 2015
(3) Data Quality Objectives Process for Superfund, Publication 9355.9-01FS, EPA/540/F-93/043
(4) https://www.epa.gov/sites/production/files/documents/guidance_systematic_planning_dqo_process.pdf
Response: EPA has decided not to finalize the proposed rule change that would have eliminated MSHA quarterly reports as an accepted monitoring method under 40 CFR 98.324(b). See Section III.R.2 of the preamble to the final rule for additional information. The EPA is also not making any changes to the rule regarding the frequency of required monitoring from quarterly to monthly for those mines using grab samples. In the preamble to the proposed rule (81 FR 2566), we sought comment on increasing the sampling frequency for reporters using grab samples from quarterly to monthly in order to provide more accurate and reliable data. We specifically asked for commenters to submit studies, data, and background information demonstrating multi-year ventilation air methane monitoring that is more frequent than quarterly.  No commenters provided additional data or information to support changes to the monitoring frequency, therefore no such changes are being made to the rule at this time.
EPA also wishes to address the comments regarding the coal industry's contribution to U.S. greenhouse gas emissions. EPA disagrees with the commenter's assertion that the coal industry is an insignificant contributor to the U.S. total. Coal mines are the fourth largest source of methane, a key contributing greenhouse gas with a Global Warming Potential 25 times greater than CO2. Moreover, as individual point sources, coal mines can be very large emitters. In 2014, 128 reporting mines emitted 43 million metric tons of CO2 equivalent (MtCO2), with average greenhouse gas emissions per facility of 336,000 MtCO2 per year.
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Commenter Name:  Laura M. Goldfarb, Counsel, Steptoe & Johnson
Commenter Affiliation:  Arcelor Mittal Princeton
Document Control Number:  EPA-HQ-OAR-2015-0526-0061
Comment Excerpt Number:  5
Comment: Increased sampling frequency from quarterly to monthly will be an unnecessary burden.
EPA is "seeking comment on increasing the sampling frequency for reporters using grab samples from quarterly to monthly In order to provide more accurate and reliable data." EPA notes that "[c]urrently, mines that monitor methane liberation from grab samples must take at least one grab sample per quarter for each ventilation monitoring point (40 CFR 98.324(b)(1)), and report methane liberation on a quarterly basis." Mine specific daily and weekly data sets show that significant day-to-day and week-to-week variation in methane emissions can occur depending on operating and geologic conditions at a mine.
The fluctuating measurements cited by EPA as a basis for its proposal can be overcome using far more efficient methods than the burdensome additional sampling requirements proposed by the Agency. ArcelorMittal suggests the return on investment in resources used for additional sampling is insufficient to justify EPA imposing this unnecessary burden on operators. For example, in order to collect its own grab samples instead of using the current MSHA ventilation data, the company would have to invest significant financial resources to:
 Develop sampling plan/written protocols per 98.324(b)(l) procedure for grab sampling (based on MSHA PH-08-V-1) to develop procedures)
 Train appropriate personnel (or possibly hire and train a new employee depending on the volume of work to be performed) (labor$ to train and manage)
 Perform monthly sampling at each ventilation point, the same points MSHA currently measures, and collect the following each time:
 Date & location
 Flow
 Temperature
 Pressure
 Moisture
 Methane concentration (percent)
 Submit for lab analysis by GC (ASTM 01945-03 or other per 98.324(d)(l)). Note that Method 25A (portable flame ionization analyzer) can be used to measure samples in the field but triplicate samples are needed and more detailed procedures apply (plus possibly needing to purchase or rent an instrument).
 Review reports and compile data (this step is basically the same as for using the MSHA ventilation data)
Arcelor believes that requiring this process is unnecessary and overly burdensome on operators given available alternative data collection and verification methods. ArcelorMittal also asserts that these proposed costs will have significant impacts on the already strained financial condition facing it and many other coal mining companies.
As an alternative to the proposal, EPA should consider having reporters sample on a quarterly basis and at major ventilation plan changes, and urges EPA to include such an option in the final rule.
Response: EPA has decided not to finalize a proposed rule change that would have eliminated MSHA quarterly reports as an accepted monitoring method under 40 CFR 98.324(b). See Section III.R.2 of the preamble to the final rule for additional information. The EPA is also not making any changes to the rule regarding the frequency of required monitoring from quarterly to monthly for those mines using grab samples. In the preamble to the proposed rule (81 FR 2566), we sought comment on increasing the sampling frequency for reporters using grab samples from quarterly to monthly in order to provide more accurate and reliable data. We specifically asked for commenters to submit studies, data, and background information demonstrating multi-year ventilation air methane monitoring that is more frequent than quarterly.  No commenters provided additional data or information to support changes to the monitoring frequency, therefore no such changes are being made to the rule at this time.
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Commenter Name:  Bruce Watzman
Commenter Affiliation:  National Mining Association (NMA)
Document Control Number:  EPA-HQ-OAR-2015-0526-0051
Comment Excerpt Number:  5
Comment: We understand EPA's reasoning that increasing sampling frequency will facilitate less variability and more consistency in quality of data. However, there is a more practical approach to ensuring quality data and consistency. Specifically, EPA can improve accuracy utilizing VAM variance data to calculate the emission range instead of requiring additional sampling. The comparison evaluation of estimated emissions using the quarterly data along with the VAM variances is most simpler, less costly, and probably with a + or  -  5 percent accuracy of actual data collected. This approach would enable EPA to more accurately capture the potential emissions based on quarterly sample results. Also this approach eliminates additional and unnecessary sampling and the increased costs that would be imposed to calculate a reasonable number of CO2e emissions for the underground coal mine sector. Overall, the CO2e emissions that are being emitted underground combined with the variance ranges from the VAM evaluation will result in a more appropriate calculation of the potential based on EPA's research. This is a more practical and reasonable approach when you consider the minor impact that underground coal mining is having on the 1.3 percent of the overall CO2e emissions. It makes no sense to collect this additional information through increased sampling when the overall emissions added to the big picture in unnoticeable. NMA urges EPA to apply the quarterly estimated measurements using the VAM variances instead of the actual monthly measurements.
Response: See the response to comment EPA-HQ-OAR-2015-0526-0061, Excerpt 5.
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Comments on Subpart FF Issues not proposed
Commenter Name:  Laura M. Goldfarb, Counsel, Steptoe & Johnson
Commenter Affiliation:  Arcelor Mittal Princeton
Document Control Number:  EPA-HQ-OAR-2015-0526-0061
Comment Excerpt Number:  1
Comment: Although comments were not specifically requested on this Issue, ArcelorMittal believes that the reporting threshold for subpart FF of 36,500,000 cubic feet of CH4/year is not appropriate. Mining industry emissions reports appear to be dominated by a small group of large emitters. ArcelorMittal suggests that operators of lesser emitting mines are being unnecessarily drawn into the subpart FF reporting program because of the arbitrarily chosen reporting threshold. For example, ArcelorMittal contributes approximately .06% of total emissions (based on prior reporting), and yet it is treated the same as higher-emitting mines. ArcelorMittal therefore urges EPA to establish the reporting threshold at a level that will still require large emitters to report but will not burden smaller emitting mine operators with the same reporting requirements.
Response: Because EPA did not solicit comment on changes to the reporting threshold, EPA did not consider whether to change that threshold in the final rule. The decision to establish the threshold at 36.5 million cubic feet per year was explained in the final rule adopted in 2010 (75 FR 39736).
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Revisions to Subpart HH
Improve Quality: Request for comment on option for reporters to use either an area-weighted average or a volume-weighted average approach to determine collection efficiency
Commenter Name:  Kerry Kelly and Amy Van Kolken Banister
Commenter Affiliation:  Waste Management (WM)
Document Control Number:  EPA-HQ-OAR-2015-0526-0049
Comment Excerpt Number:  8
Comment: The Agency seeks comments on whether revisions should be made to Table HH-3 to allow landfill owner/operators to determine weighted average collection efficiency using the current area-based approach, a volume-based approach, the option of using either approach, or the requirement to use one of the two approaches based on unspecified landfill characteristics. EPA poses a question in the preamble whether reporters should be given the option to calculate collection efficiency. (81 FR 2568)
We first want to address this question by stating our unequivocal support for maintaining the ability for reporters to calculate a weighted-average collection efficiency value for each landfill using an area-based approach. Landfill reporters have used this methodology since the inception of the GHG Reporting Program (GHGRP). EPA adopted the methodology based upon a review of substantial, peer-reviewed scientific data supporting the approach. EPA did this to enhance the accuracy of GHG emissions estimates by incorporating actual site-specific data about the type of landfill cover employed. This allows the GHGRP to go beyond simple modeling using default values, and results in improved emission estimates through use of site-specific values for calculating collection efficiency. The Agency would undermine the quality of the GHGRP data and its usefulness in enhancing the U.S. GHG Inventory data if it were to disallow use of the area-weighted average collection efficiency.
WM has carefully considered the potential impacts of switching from an area-based to a volume-based approach for calculating collection efficiency. Our primary concern is that the volume-based approach has no basis in the peer-reviewed scientific literature as underpins EPA's development of the current collection efficiency calculation. Waste depth and refuse volume were not parameters considered in the peer-reviewed studies, so their effect on collection efficiency is undetermined. We thus see no rationale for using a volume-based approach in the absence of peer-reviewed studies that establish a causal relationship between collection efficiency and refuse volume. Absent such an essential technical basis for establishing a volume-based approach, we recommend that the Agency maintain the current area-based method for calculating collection efficiency.
Reporters subject to the GHG MRR have been using the area-based approach since 2010, and have become familiar with collecting the required data and completing the necessary calculations. Moreover, EPA has not provided any analysis or data to show that any change to this approach will improve landfill emission estimates. In fact, by introducing additional variables into the emission calculations that have not undergone review by the scientific community, EPA may actually increase the uncertainty of the landfill emissions estimates rather than improve their accuracy.
We also are concerned the EPA will prescribe the use of one or the other method based on site characteristics that the Agency has yet to specify. Moreover, it is unclear whether EPA would require additional documentation to support use of the volume-based approach. Since the Agency has neither identified specific landfill characteristics for determining use of the "appropriate" collection efficiency method, nor the scientific basis for doing so, implementation of this new approach will very likely cause confusion for reporters while increasing uncertainty in the estimates.
Based on our analysis of utilizing the two approaches in calculating collection efficiency, we see no appreciable benefit to revising the current methodology, are concerned it will increase the uncertainty of the estimates, and see no technical or scientific basis for using a volume-based approach. WM, therefore, recommends continuing sole use of the area-based method for calculating collection efficiency.
Response: EPA is not finalizing proposed revisions to the method to calculate the gas collection efficiency, thus reporters will continue to be required to use the current area-based approach as defined in Table HH-3. See Section III.S.2 of the preamble to the final rule for EPA's response to this comment.
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Commenter Name:  Anne Germain and David Biderman
Commenter Affiliation:  National Waste & Recycling Association (NWRA) and Solid Waste Association of North America (SWANA)
Document Control Number:  EPA-HQ-OAR-2015-0526-0057
Comment Excerpt Number:  3
Comment: Area-based vs. volume-based weighting collection efficiency
EPA is seeking comment on whether revisions should be made to Table HH - 3 to allow landfill owners or operators to determine the weighted average collection efficiency for their landfill using an area-based weighting approach, a volume-based weighting approach, whether reporters should have the option of using either approach, or if one approach should be required if certain landfill characteristics are met.
EPA initially selected the area-based approach to improve GHG emissions estimates by incorporating site-specific cover data. The site-specific data improves emissions estimates over simply modeling emissions using default values. Our members support maintaining the ability to calculate a weighted average collection efficiency value using the area-based approach.
EPA notes that reporters have stated the area-based approach might not accurately reflect the overall efficiency of the gas collection system due to differences in waste depth or age of waste. We are concerned EPA has not identified site-specific characteristics for determining when a volume-based approach should be used, the information and process for determining a volume-based collection efficiency, or the scientific basis for using such an approach. Without first developing this essential information, we believe this new approach will simply cause confusion for reporters and may undermine the accuracy of emissions estimation.
Further, unlike the area-based approach, the volume-based approach is not based on any peer-reviewed scientific literature. Waste depth and refuse volume were not factors evaluated in the research underpinning the area-based approach, so their effect is unknown. Given that, we see no technical basis for changing the approach for calculating collection efficiency. Therefore, NWRA and SWANA recommend maintaining the area-based approach and eliminating any requirement for these reporters to include average waste depth, as this data element is not used in emissions calculations.
Response: EPA is not finalizing proposed revisions to the method to calculate the gas collection efficiency, thus reporters will continue to be required to use the current area-based approach as defined in Table HH-3. See Section III.S.2 of the preamble to the final rule for EPA's response to this comment.
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Improve Quality: Revisions to include alternative final covers in area type A5 (Table HH-3)
Commenter Name:  Kerry Kelly and Amy Van Kolken Banister
Commenter Affiliation:  Waste Management (WM)
Document Control Number:  EPA-HQ-OAR-2015-0526-0049
Comment Excerpt Number:  6
Comment: The Agency proposes to broaden the description of landfill areas in Table HH-3 to allow final covers that do not meet the exact language in the definition for area type A5 to use the 95% collection efficiency in their emissions calculations. WM supports this proposal, but recommends clarifying language to avoid ambiguity. The federal and state regulatory frameworks for landfills (Subtitle D of the Resource Conservation and Recovery Act (RCRA), state solid waste rules) commonly use three terms to define landfill cover: daily cover, intermediate cover and final cover. States are required to approve final covers that that [sic]meet federal performance requirements, or requirements that are at least as stringent. RCRA authorizes States to approve final covers with designs or materials that differ from the federal performance requirements as long as the state determines that they are equally protective. As EPA noted in the preamble, these landfills may not meet the exact description of area type 5A, but they are approved by state regulatory agencies as meeting or exceeding federal performance requirements. It is therefore appropriate that these final covers also qualify to use the 95% collection efficiency.
These covers are typically called, simply, "final covers," and so to ensure that GHG MRR terminology closely tracks that of RCRA Subtitle D and implementing state regulations, we recommend EPA define "final cover" as opposed to "alternative final cover" as it proposes. This would have the advantage of clearly defining all the cover types that are used in GHG MRR emissions calculations. We therefore suggest the following definition of final cover to be used in lieu of the proposed "alternative final cover" definition.
Final cover means materials used at a landfill that meets final closure regulations of the competent federal, state, or local authority.
We also suggest corresponding edits to Tables HH-3 and HH-4 to comport with the new definition and have included these suggested changes in Attachment A of our comments.
[Note: The commenter submitted a revised version of Tables HH-3 and Tables HH-4 in Appendix A. See DCN EPA-HQ-OAR-2015-0526-0049 for additional details.]
Response: EPA is finalizing a definition of final cover in 40 CFR 98.348 instead of the proposed definition of "alternative final cover" with minor edits to Tables HH-3 and HH-4. See Section III.S.2 of the preamble to the final rule for EPA's response to this comment.
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Commenter Name:  Anne Germain and David Biderman
Commenter Affiliation:  National Waste & Recycling Association (NWRA) and Solid Waste Association of North America (SWANA)
Document Control Number:  EPA-HQ-OAR-2015-0526-0057
Comment Excerpt Number:  8
Comment: EPA proposes to broaden the description of landfill areas in Table HH-3 to allow final covers that do not meet the exact language in the definition for area type A5 to use the 95% collection efficiency in their emissions calculations. While NWRA and SWANA support this proposal, we recommend that EPA add a definition for final cover, which would include alternative covers that meet federal requirements and are approved by state regulatory authorities. We recommend the following language:
"Final cover means materials used at a landfill that meets final closure regulations of the competent federal, state, or local authority."
We have also made suggested clarifying edits to Tables HH-3 and HH-4, which are consistent with the new definition as well as the suggested usage of only area-based weighting. The suggested changes are included in Attachment A.
[Note: The commenter submitted a revised version of Tables HH-3 and Tables HH-4 in Appendix A. See DCN EPA-HQ-OAR-2015-0526-0057 for additional details.]
Response: EPA is finalizing a definition of final cover in 40 CFR 98.348 with minor edits to Tables HH-3 and HH-4. See Section III.S.2 of the preamble to the final rule for EPA's response to this comment.
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Commenter Name:  Ted Michaels
Commenter Affiliation:  Energy Recovery Council (ERC)
Document Control Number:  EPA-HQ-OAR-2015-0526-0033
Comment Excerpt Number:  3
Comment: The EPA has proposed to expand the types of covers which can claim a 95 percent collection efficiency without providing any data to document the ability of these covers to attain or sustain this level of performance. This is especially problematic in that a 95% collection efficiency is not supported by the agency's own research and the consensus default arrived by a group of experts and stakeholders convened by the U.S. EPA at a Landfill Gas Experts Meeting held in October 2014.[2,3] The EPA's Waste Reduction Model (WARM) uses 90% collection efficiency for final covers.[4]
Even 90% is likely too high. The California Air Resources Board, having implemented far more stringent landfill gas control regulations than those in the current federal landfill emission guidelines, has determined that they can achieve an instantaneous gas collection efficiency of 83%, after final cap and cover.[5] Measured methane emissions from the Puente Hills landfill, a well-managed landfill with a 6 foot think clay cap located in a dry climate, fully in compliance with the CARB requirements, were indicative of a 73% collection efficiency.[6]  Use of an overly optimistic collection efficiency figure results in an under-reporting of landfill gas emissions which could lead to landfills not receiving the policy focus needed to ensure a low carbon future.
Footnotes:
(2) U.S. EPA (2012) Quantifying Methane Abatement Efficiency at Three Municipal Solid Waste Landfills. http://www.epa.gov/nrmrl/pubs/600r12003.html
(3) See p.5 of Levis, J. & Barlaz, M.A. (2014) Landfill Gas Monte Carol Model Documentation and Results. http://epa.gov/epawaste/conserve/tools/warm/pdfs/lanfl_gas_mont_carlo_modl.pdf.
(4) See Exhibit 7‐9 of U.S. EPA (2015) Documentation for Greenhouse Gas Emission and Energy Factors Used in the Waste Reduction Model (WARM).
(5) California Air Resources Board (CARB 2009), Staff Report: Initial Statement of Reasons for the Proposed Regulation to Reduce Methane Emissions from Municipal Solid Waste Landfills, Appendix D: Evaluation of Landfill Gas Collection Efficiency, May 2009. Available at: http://www.arb.ca.gov/regact/2009/landfills09/isor.pdf
(6) Peischl et al. estimated emissions from the Puente Hills Landfill to be 34 Gg / yr, comparable to the 2008 CARB inventory value of 38.8 Gg / yr. When the measured emissions of the Puente Hills landfill are compared against published data on landfill gas collection at the site [Shan et al. (2012) Estimation of Landfill Gas Emissions and Collection System Efficiency Using Surface Flux Chamber Technology  -  A Case Study of Puente Hills Landfill, SWANA 35th Annual Landfill Gas Symposium Proceedings.], the overall abatement efficiency inclusive of the effects of soil oxidation is 74.7%. Assuming soil oxidation of 10%, the resultant collection efficiency is 73%.
Response: The proposed revision referenced by the commenter was to add the term "alternative final cover." However, as discussed in Section III.S.2 of the preamble to the final rule, Subpart HH is amended in the final rule to include a definition of final cover, rather than alternative final cover, and final cover is defined as materials used at a landfill that meet the final closure regulations of the relevant federal, state, or local authority. The relevant federal, state, or local authority approves the composition and design of a final cover, after considering documentation provided by the regulated entity showing that the final cover demonstrates the required performance (as defined in the RCRA requirements for MSW landfills). If the relevant authority determines that a final cover will meet the applicable requirements, the same collection efficiency should apply.
With regard to the general comment that the 95% collection efficiency is not supported currently in the rule, EPA did not solicit comment on this topic and it is therefore outside of scope for this rulemaking. Please see Docket ID No. EPA-HQ-OAR-2012-0934-0127 page 183, excerpt 6 for previous discussion of this topic.
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Commenter Name:  Paul Gilman
Commenter Affiliation:  Covanta
Document Control Number:  EPA-HQ-OAR-2015-0526-0034
Comment Excerpt Number:  4
Comment: The EPA has proposed to expand the types of covers which can claim a 95 percent collection efficiency without providing any data to document the ability of these covers to attain or sustain this level of performance. This is especially problematic in that a 95% collection efficiency is not supported by the agency's own research and the consensus default arrived by a group of experts and stakeholders convened by the U.S. EPA at a Landfill Gas Experts Meeting held in October 2014.[2,3] The EPA's Waste Reduction Model (WARM) uses 90% collection efficiency for final covers.[4]
Even 90% is likely too high. The California Air Resources Board, having implemented far more stringent landfill gas control regulations than those in the current federal landfill emission guidelines, has determined that they can achieve an instantaneous gas collection efficiency of 83%, after final cap and cover.[5]  Measured methane emissions from the Puente Hills landfill, a well-managed landfill with a 6 foot think [sic] clay cap located in a dry climate, fully in compliance with the CARB requirements, were indicative of a 73% collection efficiency.6 Use of an overly optimistic collection efficiency figure results in an under-reporting of landfill gas emissions which could lead to landfills not receiving the policy focus needed to ensure a low carbon future.
Footnotes:
(2) U.S. EPA (2012) Quantifying Methane Abatement Efficiency at Three Municipal Solid Waste Landfills. http://www.epa.gov/nrmrl/pubs/600r12003.html
(3) See p.5 of Levis, J. & Barlaz, M.A. (2014) Landfill Gas Monte Carol Model Documentation and Results. http://epa.gov/epawaste/conserve/tools/warm/pdfs/lanfl_gas_mont_carlo_modl.pdf.
(4) See Exhibit 7‐9 of U.S. EPA (2015) Documentation for Greenhouse Gas Emission and Energy Factors Used in the Waste Reduction Model (WARM).
(5) California Air Resources Board (CARB 2009), Staff Report: Initial Statement of Reasons for the Proposed Regulation to Reduce Methane Emissions from Municipal Solid Waste Landfills, Appendix D: Evaluation of Landfill Gas Collection Efficiency, May 2009. Available at: http://www.arb.ca.gov/regact/2009/landfills09/isor.pdf
(6) Peischl et al. estimated emissions from the Puente Hills Landfill to be 34 Gg / yr, comparable to the 2008 CARB inventory value of 38.8 Gg / yr. When the measured emissions of the Puente Hills landfill are compared against published data on landfill gas collection at the site [Shan et al. (2012) Estimation of Landfill Gas Emissions and Collection System Efficiency Using Surface Flux Chamber Technology  -  A Case Study of Puente Hills Landfill, SWANA 35th Annual Landfill Gas Symposium Proceedings.], the overall abatement efficiency inclusive of the effects of soil oxidation is 74.7%. Assuming soil oxidation of 10%, the resultant collection efficiency is 73%.
Response: See response to comment EPA-HQ-OAR-2015-0526-0033, Excerpt 3.
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Commenter Name:  Kerry Kelly and Amy Van Kolken Banister
Commenter Affiliation:  Waste Management (WM)
Document Control Number:  EPA-HQ-OAR-2015-0526-0049
Comment Excerpt Number:  7
Comment: Covanta and ERC commented that EPA should lower the collection efficiency value for area type A5 from 95% to 90%. They asserted that such a change would align the value with "current scientific consensus."  However, the value is already in line with scientific consensus as reported in the peer-reviewed literature and studies on LFG collection efficiency. Many of these articles and studies were included in the references supplied to EPA by SWICS (2008), which informed the range of values for collection efficiency reporters may employ under Subpart HH. Furthermore, the "scientific consensus" Covanta refers to is a stakeholder process EPA used to obtain advice about updating its Waste Reduction Model (WARM). EPA, however, advises against use of the WARM model for GHG inventory purposes, and provides an explicit disclaimer to using it for annual or any other type of inventory of emissions.[10] The conclusions made in the SWICS report remain valid, and are supported by more recent field studies of whole landfill emissions, which suggest that the range of LFG collection efficiencies for final covers range from 90-99%.
When developing Subpart HH, EPA selected the mid-range value of 95% to represent the average collection efficiency for final covers across the U.S. and selected the mid-range value for other cover types. WM supports the continued use of the 95% value final covers as it is well supported by the literature and field measurements; we have seen no data to suggest that this value should be changed. We do note that by applying a single default value for final covers, this prevents a landfill from ever improving its collection efficiency by making improvements to its GCCS. As Barlaz et al. 2009 concluded, "If emissions were to be calculated based on gas collected and a set gas collection efficiency... [as in the GHG MRR] then the calculated emissions would increase with the volume of gas collected when in fact, emissions decrease as more gas is collected.[11] Therefore, use of a single default for each cover type in Subpart HH may result in an overestimate of GHG emissions for those landfills, particularly those with final covers and very comprehensive GCCS. However, WM understands the Agency's goals of both scientific validity and ease of administration, and continues to support the 95% value for final covers.
Footnotes:
(10) "This [WARM] life-cycle approach is not appropriate for use in inventories because of the diffuse nature of the emissions and emission reductions within a single emission factor."  U.S. EPA, Subsection Note to Waste Reduction Model, (WARM), https://www3.epa.gov/warm/index.html (last updated Feb. 23, 2016).
(11) Barlaz, M., Chanton, J., Green, R., 2009, Controls on Landfill Gas Collection Efficiency: Instantaneous and Lifetime Performance, Journal of the Air & Waste Management Association, 59: 1399-1404
Response: EPA did not solicit comment on a revision to the 95% collection efficiency for landfills with final covers meeting the criteria for area type A5 in Table HH-3 and therefore this comment is outside of scope for this rulemaking. The revision that was proposed for A5, was to add the term "alternative final cover." However, as discussed in Section III.S.2 of the preamble to the final rule, Subpart HH is amended in the final rule to include a definition of final cover, rather than alternative final cover, and final cover is defined as materials used at a landfill that meet the final closure regulations of the relevant federal, state, or local authority. See comment EPA-HQ-OAR-2015-0526-0033, Excerpt 3 for the comment response this commenter mentioned.
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Commenter Name:  Anne Germain and David Biderman
Commenter Affiliation:  National Waste & Recycling Association (NWRA) and Solid Waste Association of North America (SWANA)
Document Control Number:  EPA-HQ-OAR-2015-0526-0057
Comment Excerpt Number:  4
Comment: Covanta, a major waste-to-energy service provider, and the Energy Recovery Council (ERC), the trade association representing the waste-to-energy industry, have provided comments on the proposed changes. In particular, they suggest the collection efficiency included in the rule is too high, by citing work done by the California Air Resources Board (CARB), and the example of Puente Hills Landfill. They state that CARB determined the instantaneous gas collection efficiency was only 83% after final cap and cover.
In fact, the Los Angeles County Sanitation Districts (LACSD) developed a method to determine landfill gas collection efficiency utilizing actual landfill integrated surface gas monitoring data combined with air dispersion modeling. This method, which was termed the ISM/ISC methodology, was first reported in a study evaluating landfill gas collection efficiency at LACSD's Palos Verdes Landfill in 2006.[1] In 2007, LACSD repeated the landfill gas collection efficiency study after further enhancements were made to the Palos Verdes Landfill collection system.[2] However, this study was accompanied by a field study to directly measure fugitive emissions from the landfill through the use of flux chambers. This study verified the effectiveness of the landfill gas collection system enhancements by increasing the calculated landfill gas collection efficiency to over 99%, but more importantly, the ISM/ISC methodology was field verified using flux chambers. This study was conducted with the oversight of the State of California Department of Toxics Substance Control.
During the development of its regulation to reduce methane emissions from solid waste landfills, the California Air Resources Board (CARB) reached out to LACSD for help in calculating landfill gas collection efficiency for well-controlled landfills. LACSD's staff briefed CARB on the ISM/ISC methodology, which CARB adopted for use in its rule for determining the effectiveness of state-of-the-art landfill gas collection systems. However, CARB staff made a number of modifications to the LACSD approach that effectively lowered the expected landfill gas collection efficiency in its 2007 study to below 85%, which conflicted with the field-verified ISM/ISC methodology. LACSD outlined in a letter to Ms. Mary Nichols (Chair, California Air Resources Board)[3] in great detail why the CARB approach was inappropriate, however, CARB still proceeded with its very conservative approach.
Covanta's letter failed to recognize the conservative nature of the 83% calculation (actually, CARB used 85% in the CARB Staff Report cited by Covanta) compared to the original approach provided by LACSD. In addition, Covanta indicated in error that the collection efficiency was applied "after final cap and cover." In fact, Table IV-3, Estimated Methane Emission Reductions, of the CARB Staff Report cited by Covanta, applies an 85% collection efficiency to 106 landfills without consideration of whether sites had a final cap and cover.
Covanta further contends that EPA's use of collection efficiencies, in excess of 90%, is too high, citing Puente Hills Landfills as having a 73% collection efficiency. This value appears to have been somehow calculated from studies conducted by Peischl et al.4 However, the number was not included in the actual studies.
Studies by Peischl et. al., and similar studies by Wong et. al.[5], utilize airborne and sophisticated fixed laser type measurements to derive methane emission rates. These measurements provide a gross indication of methane emissions, but generally have poor spatial resolution. Puente Hills Landfill is located in an urban area near other potential leak sources including oil and gas fields. As such, it is difficult to assign any detected methane to a particular source. Typically, follow up to the lasers are conducted with ground level detection devices to pinpoint the methane sources. This ground-truthing was not conducted by the study authors. Covanta then used this questionable data and somehow derived the 73% landfill gas collection efficiency cited in their letter.
Extensive field measurements have been taken to determine methane emission rates and landfill gas collection efficiency at Puente Hills, as well as other LACSD-operated landfills. Initial field work was conducted at the Palos Verdes Landfill2 which indicated a 99% collection efficiency, but later field work was conducted and reported in 2013[6] for the LACSD-operated Puente Hills, Calabasas and Scholl Canyon Landfills. This study used flux chambers to measure surface emissions, coupled with a comprehensive method to identify random sample locations representative of the landfill sites. The results of the published study indicated collection efficiencies of 95.9%, 94.8% and 97.2% for the Puente Hills, Calabasas, and Scholl Canyon landfills, respectively. All three of these landfills were active sites at the time of the study. Therefore, we recommend that EPA utilize the proposed collection efficiencies.
Footnotes:
(1) Huitric, R. and D. Kong (2006) "Measuring landfill gas collection efficiency using surface methane concentrations", Solid Waste Association of North America (SWANA) 29th Landfill Gas Symposium, St. Petersburg, FL.
(2) Huitric, R., D. Kong, L. Scales, S. Maguin, and P. Sullivan (2007) "Field comparison of landfill gas collection efficiency measurements", Solid Waste Association of North America (SWANA) 30th Landfill Gas Symposium, Monterey, CA.
(3) Caponi, F. (May 22, 2009). Letter to Ms. Mary Nichols, Comments on the Staff Report: Initial Statement of Reasons for the Proposed Regulation To Reduce Methane Emissions from Municipal Solid Waste Landfills, Appendix D  -  Evaluation of Landfill Gas Collection Efficiency.
(4) Peischl et al. (2013) Quantifying sources of methane using light alkanes in the Los Angeles basin, California, J. Geophys Res., Vol 118, 1-17.)
(5) Wong et al. (2015) Mapping CH4:CO2 ratios in Los Angeles with CLARS-FTS from Mount Wilson, California, Atmos. Chem. Phys., 15, 241-252. (6) Shan, et al. (2013) "Estimating Greenhouse Gas Emissions from Three Southern California Landfill Sites", Solid Waste Association of North America (SWANA) 36th Landfill Gas Symposium.

Response: See response to comment EPA-HQ-OAR-2015-0526-0049, Excerpt 7.
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Other Amendments: Revision of soil cover requirements and definition of intermediate or interim soil cover (Table HH-4)
Commenter Name:  Kerry Kelly and Amy Van Kolken Banister
Commenter Affiliation:  Waste Management (WM)
Document Control Number:  EPA-HQ-OAR-2015-0526-0049
Comment Excerpt Number:  1
Comment: WM commends EPA for granting our Petition for Reconsideration by revising Table HH-4 in Subpart HH of the GHG MRR to remove the condition that "flux dependent soil oxidation fractions" may be used only by landfills with at least 24 inches of soil cover over a majority of the landfill area containing waste. (81 FR 2569) EPA proposes to replace the 24-inch soil cover requirement with a prerequisite that landfills using flux dependent soil oxidation fractions (also referred to as the "binned approach") must have "intermediate or interim soil cover" as defined by a given state[1] over 50% or more of the landfill area containing waste. WM believes this approach will allow landfills with actual methane oxidation fractions greater than 10% to report more accurately their GHG emission rates. Furthermore, the proposed change is consistent with numerous studies and field data that clearly demonstrate that depth of soil cover is not a significant variable influencing methane flux rates at MSW landfills.
EPA has acknowledged that the revision to Table HH-4 is in response to WM's Petition for Reconsideration and that the 2015 Revisions are meant to "complete [EPA's] response to" WM's petition. (81 FR 2569) We are pleased with the Agency's response to our petition.
Footnotes:
(1) In the event that a landfill is located in a state that has not defined "intermediate or interim soil" cover, EPA has proposed that a landfill must have a minimum of 12 inches of soil cover to use an oxidation fraction of 0.25 or 0.35. 81 Fed. Reg. at 2569-70.
Response: EPA acknowledges this supportive comment and is finalizing the proposed revisions. As stated in section III.S.1.c of the preamble to the final rule, the EPA is completing its response to the Petition for Reconsideration through this final rulemaking.
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Commenter Name:  Kerry Kelly and Amy Van Kolken Banister
Commenter Affiliation:  Waste Management (WM)
Document Control Number:  EPA-HQ-OAR-2015-0526-0049
Comment Excerpt Number:  2
Comment: While there exists a strong technical foundation of peer-reviewed literature for the proposal to remove the 24-inch soil cover requirement, EPA has an opportunity to strengthen the scientific basis for its proposal in the Final Rule. WM believes that the technical arguments and rationale for the revision to Table HH-4 in both the preamble to the 2015 Revisions and EPA's technical support memorandum entitled "Review of Oxidation Studies and Associated Cover Depth in the Peer-Reviewed Literature" (RTI Memo) are buttressed by clear scientific support for removing the 24-inch soil cover requirement. Nonetheless, EPA should confirm in the preamble discussion to the final rule that depth of soil cover is not the sole, or master variable for determining methane flux.
In explaining the grant of WM's Petition for Reconsideration, EPA states in the preamble that EPA "re-evaluated the available peer-reviewed literature (27 studies) at the time of proposal regarding soil oxidation fractions." (81 FR 2569) EPA then states that based on this review it "found that 85 percent of the data points in the literature where both methane oxidized and cover depth were reported had a cover depth of 24 inches or more." (81 FR 2569) According to EPA, "this investigation confirmed that the vast majority of the soil oxidation studies were performed on landfills with cover depths of 24 inches or more, which was the basis for the 24 inch soil cover requirement in the 2013 Rule." (81 FR 2569) EPA further explains, however, that several of the studies that EPA re-evaluated "indicated that a majority of the soil oxidation occurs in the top 12 to 15 inches of the soil cover." (81 FR 2569) According to EPA, "some of the data support the idea that the bulk of the oxidation may occur in the top 12 to 15 inches of soil," but that "it is unclear whether these soils would have had similar oxidation rates if only 12 to 15 inches of soil cover were present." (81 FR 2569)
EPA's characterization of the soil oxidation studies still overstates the significance of depth of soil cover as a possible factor influencing methane oxidation, as the relevant peer-reviewed studies in the record do not suggest that there is any correlation between depth of soil cover and methane flux. Stakeholders could view the Agency's focus on the measurements where both cover depth and oxidation rates are reported (a minority of the relevant data), to mean that the oxidation studies identified depth of soil cover as a significant variable influencing methane oxidation, which they did not. Given that the best available science does not support a conclusion that depth of soil cover influences methane oxidation, EPA should consider bolstering its decision to replace the 24-inch soil cover requirement with intermediate or interim soil cover, by more comprehensively describing the underlying literature when it finalizes the 2015 Revisions.
In proposing the binned approach, EPA relied on the methane oxidation studies set forth in the SWICS addendum entitled, "SWICS 2.2 Methane Oxidation Addendum 2012," included in the docket for the 2013 Rule at Docket I.D. No. EPA-HQ-OAR-2012-0934-0088 (the "SWICS Addendum"). Table 2 in the SWICS Addendum lists 95 measurements. In its Petition for Reconsideration, WM emphasized that only 32 of those 95 measurements even reference depth of soil cover, and do so without opining on its relative influence on oxidation. Further, the authors of the majority of the SWICS Addendum studies did not consider cover depth to be a relevant factor influencing methane oxidation, as they failed to include such information. Although the remaining third of measurements referenced cover depth, the authors of those studies did not consider cover depth alone as a factor influencing methane oxidation, but rather listed a range of other factors that influence methane oxidation rates.
Though two-thirds of the data points listed in the SWICS Addendum did not consider depth of soil cover a significant enough variable to warrant mention, the preamble to the 2015 Revisions focuses on only those data points, "where both methane oxidized and cover depth were reported."  The Agency does so without noting the fact that most authors of the methane oxidation studies do not consider cover depth to be a relevant factor influencing methane oxidation rates. (81 FR 2569) Furthermore, where study authors report soil cover depth, they include it as only one of a range of factors that may influence methane oxidation.
Thus, the relevant scientific data makes clear that soil cover depth is an inappropriate prerequisite for use of the binned approach. Therefore, EPA should not overemphasize the importance of the small minority of measurements; especially considering that suggestions that cover depth and methane oxidation are related is inconsistent with the scientific record. In the preamble to the final rule, EPA should more clearly state that the scientific record does not support 24 inches of soil cover as a reasonable and scientifically-sound prerequisite for use of the binned approach.
Response: While EPA has not adopted the commenter's specific suggestions, we have provided further explanation in section III.S.2 of the preamble to the final rule regarding the final revisions to the rule in response to the Petition for Reconsideration.
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Commenter Name:  Kerry Kelly and Amy Van Kolken Banister
Commenter Affiliation:  Waste Management (WM)
Document Control Number:  EPA-HQ-OAR-2015-0526-0049
Comment Excerpt Number:  3
Comment: In further explaining the basis for replacing the 24-inch soil cover requirement with intermediate or interim soil cover, EPA directs readers to review the RTI Memo in the rule docket, which provides additional detail on the review of the soil oxidation literature. (81 FR 2569, EPA Docket ID No. EPA-HQ-OAR-2015-0526-0008) The RTI Memo correctly notes that methane oxidation rates are influenced by a number of variables including: (1) "The flow velocity of landfill gas, or the methane flux, through the soil surface"; (2) "The porosity of the soil layer"; (3) "The number and types of microorganisms in the surface soil layer"; and (4) "The soil surface temperature and moisture, which may increase or inhibit microbial activity." (RTI Memo at 1). EPA rightly considered these factors when it proposed the original binned approach on April 2, 2013 and did not propose a minimum soil cover requirement. (78 FR 19802) At that time, EPA correctly noted that the "methane flux rate entering the soil layer" is the "key variable" for determining methane oxidation. (78 FR 19825) As a result, EPA proposed "[t]hree different default oxidation fractions depending on the methane flux bin." (RTI Memo at 2) RTI explains that the original binned approach was meant to "provide a more realistic estimate of the role of methane oxidation in the surface soil on the methane emissions than the single default oxidation fraction" of 10%. (RTI Memo at 2)
EPA's original proposal for the binned approach would have allowed any MSW landfill to take advantage of the larger oxidation fractions depending on site-specific methane flux rates. However, RTI explains that the 24-inch soil cover requirement was subsequently added as a response to a comment from the Center for a Competitive Waste Industry ("CCWI"), which noted that "`oxidation only occurs in landfill covers that are comprised only of soil (with the necessary depth, porosity, temperature and microbes), and not through composite covers that include a low permeable geomembrane.'" (RTI Memo at 2) Though CCWI did not comment directly on the binned approach, and made no suggestion as to an appropriate depth of soil cover, RTI states that the "24 inch soil cover depth requirement was a logical outgrowth of these comments."[2] (RTI Memo at 2)
After describing the basis for the 24-inch soil cover requirement, the RTI Memo lists the steps taken by RTI in response to WM's Petition for Reconsideration. RTI explains that to evaluate WM's proposal to remove the 24-inch soil cover requirement RTI:
Gathered copies of all studies explicitly mentioned by WM in their petition;
Compiled information on the fraction of methane oxidized, soil cover type, and/or depth in the studies included in the WM petition as well as the studies included in SWICS 2012;
Reviewed each study to verify that all quotations cited in the petition were direct quotes; and
Determined if any additional information in the cited studies contradicts or supports the quotes used in the petition.
 (RTI Memo at 4.) In conducting its analysis, RTI reviewed only 27 of the 90 peer-reviewed landfill studies that were "included in either or both the SWICS 2012 Addendum or in RTI 2011" for "soil cover depths in relation to the oxidation fraction." (RTI Memo at 5) From these 27 studies, RTI considered only 61 out of 90 measurements, including only data points, where "both an oxidation fraction and a soil cover depth" were mentioned. (RTI Memo at 5 and 14) Neither EPA in the preamble to the 2015 Revisions, nor RTI explains why the review comprised only data points reporting both cover depth and methane oxidized.
Based on its review, RTI explains that "85% (or 52 of 61) of the data points gathered from these studies . . . had a cover depth of 24 inches or above." (RTI Memo at 15) RTI further explains that 15 of the 27 peer-reviewed studies consulted by RTI were cited in the WM Petition for Reconsideration in support of its proposal to remove the 24-inch soil cover requirement, and that "[o]f these 15 studies, 14 were conducted at landfills and 13 (93%) of these included an average cover depth of 24 inches or greater." (RTI Memo at 15)
The RTI Memo fails to acknowledge that WM conducted a detailed review of the 15 studies cited in its petition, and described the authors' conclusions. Many authors concluded that varieties of site-specific factors influence methane oxidation, and that oxidation primarily occurs in the upper part of the cover, close to the surface of the landfill. Several of the studies did not even calculate methane oxidation at depths below 30 to 45 cm (15 to 18 inches) (WM Petition for Reconsideration at 18). Such findings are consistent with the fact that the atmosphere above the cover supplies the oxygen necessary for methane oxidation, and as the thickness of cover increases, it can become more difficult for oxygen to penetrate deep cover depths. (WM Petition for Reconsideration at 19) The cited literature shows that methane oxidation is influenced by a number of factors other than cover depth, including climate, moisture levels, and soil characteristics (2012 SWICS Addendum at 16, WM Petition for Reconsideration at 19). Thus, no single factor influencing methane oxidation is appropriate as a prerequisite for using the binned approach. (WM Petition for Reconsideration at 19)
Moreover, the RTI Memo fails to acknowledge that two-thirds of the measurements in the SWICS Addendum studies do not reference cover depth, thereby creating the impression that cover depth is more a significant variable affecting methane oxidation than the scientific data in the record indicates. Therefore, prior to finalizing the 2015 Revisions, the Agency should request that RTI revise its analysis to acknowledge that the scientific literature does not support cover depth as a primary factor influencing methane oxidation, and that two-thirds of the relevant measurements do not reference soil cover depths.