Since the release of the 2009 White Paper, a number of studies have been published in peer-reviewed literature, most notably an entire special issue of the journal Waste Management (2011) on Landfill Gas Emission and Mitigation sponsored by Consortium for Landfill Emissions Abatement Research (CLEAR). CLEAR is an International Waste Working Group (IWWG) Task Group, which focuses on landfill gas emission to the atmosphere. The group has members from 12 countries, across four continents. A number of papers in the special issue focus on the use of compost biocovers, bio-windows or permeable gas dispersion layers to treat and oxidize landfill gas in situ (Huber-Humer et al., 2011; Pedersen et al., 2011; Scheutz et al., 2011; Pawlowska et al., 2011; Dever et al., 2011; and Jung et al., 2011). Additionally, several papers in the special issue, Ranchor et al., (2011); Abichou et al., (2011) and Chanton et al., (2011b), examined the response of the methane oxidizing microbial community to methane loading to the cover soil. Two key papers, Bogner et al., (2011), and Spokas et al., (2011), describe recent work in California where field measurements of emission and oxidation were coupled with extensive modeling efforts. Chanton et al., (2011a) published the results of 37 seasonal sampling events at 20 landfills with intermediate covers over a four-year period. Abichou et al. (2011b) examined the best approach towards describing central tendencies in oxidation data and reported that the results were generally distributed normally so that mean values could be used.
In November 2012 SWICS, with the participation of Dr. Jeffrey Chanton of Florida State University and Dr. Morton Barlaz of North Carolina State University, finalized an addendum (2012 Addendum) to the Methane Oxidation section of the 2009 White Paper. The 2012 Addendum includes methane oxidation results from evaluations of 90 landfills as compared to the 47 published evaluations available in 2009. This 2012 Addendum also addresses the comments and questions EPA raised in its Response to Comments to the GHG MRR Final Rule issued October 20, 2009 (74 FR 56260):
First, EPA questioned the decision to calculate oxidation values using the arithmetic means as opposed to the median values from the array of studies, because it appeared that the means might be biased high. A more thorough discussion of this issue and inclusion of more recent literature are included in the 2012 Addendum, and both median and mean values are provided.
Second, EPA expressed some concern regarding the possible over-reliance on laboratory studies, which tend to yield higher oxidation fractions. Since release of the 2009 White Paper, governmental, academic and private researchers have made a significant number of additional field measurements, and these results are included in the addendum.
Third, EPA noted that only five field measurements for clay soils were available during development of the 2009 White Paper. Since then, significant effort has been made to measure methane oxidation at landfills with clay soils; the 2012 Addendum incorporates the results of 31 field studies.
Fourth, the 2012 Addendum addresses the variation in methane oxidation with the methane emission rate.
In reviewing and incorporating the results of these peer-reviewed studies of landfill methane oxidation, the 2012 Addendum updated the 2009 White Paper results as follows:
1. Clay cover: The number of studies in clay cover increased from five in 2009 to 31 in 2012. The mean fraction of methane oxidized increased from 18 percent to 30 percent, while the median fraction oxidized increased from 14 to 29 percent.
2. Sandy soils cover: The number of studies in sandy soils doubled from eight to 16, with the mean oxidation value changing very little (55 to 54 percent) while the median value increased from 43 to 50 percent methane oxidized.
3. "Other" covers: The number of studies in "other" cover soils increased by nine and both the mean and the median fraction oxidized values increased slightly.
4. The overall mean oxidation value across all of the studies increased from 35 to 38 percent while the overall median oxidation fraction increased from 31 to 33 percent.
Response:  Thank you for your comment. Based on a review of all comments received, we are finalizing the amendments regarding soil oxidation factors as proposed with the following exceptions. First, we are limiting the applicability of the new methane flux-dependent oxidation fractions to landfills that have a soil cover of at least 24 inches in depth for a majority of the landfill containing waste. Second, landfills that do not have a soil cover of at least 12 inches must use an oxidation factor of 0, since there is an inadequate soil layer to effect oxidation of released methane. Finally, we will allow landfills to use the default oxidation fraction of 0.10 if they elect not to calculate the methane flux rate. See Section II.R.2 of the preamble for further explanation of these exceptions.
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Commenter Name:  Kerry Kelly, Director, Federal Public & Regulatory Affairs
Commenter Affiliation:  Waste Management (WM)
Document Control Number:  EPA-HQ-OAR-2012-0934-0041-A1
Comment Excerpt Number:  16
Comment:  The SWICS 2012 Addendum Definitively Supports a Significant Increase to the Current Default Value of Ten Percent.
The 2012 Addendum concluded that the EPA default oxidation value of 10 percent underestimates typical methane oxidation and is not representative of expected methane oxidation at sites utilizing organic, clay, sand or other cover types. EPA derived the default value from one field study performed at one poorly maintained landfill with no gas collection system, Czepiel et al [Footnote: Czepiel, P.M., B. Mosher, P.M. Crill, and R.C. Harriss. 1996. Quantifying the effect of oxidation on landfill methane emissions. J. Geophys. Res. 101:16711-16719.]. Analysis of the 90 studies highlighted in the 2012 Addendum indicates that if a single value is considered for methane oxidation it should be between 33 and 38 percent.
The 2012 Addendum also examined methane oxidation as a function of methane loading to the cover layer of the landfill. Recent studies show that the percent oxidation is an inverse function of the rate of emission (Stern et al., 2007; Rachor et al., 2011; Chanton et al., 2011a,b). At lower emission rates, the methanotrophs in the soil cover can consume a larger portion of the methane delivered to them, potentially oxidizing 95 to 100 percent (Humer and Lechner, 1999, 2001a, Huber-Humer 2008; Powelson et al., 2006, 2007; Kjeldsen et al., 1997). As flux rates increase, the percent oxidation decreases and the methanotrophs can become overwhelmed with methane. Thus, as methane emission increases, percent oxidation decreases (Powelson et al., 2006, 2007).
A mathematical model of cover oxidation developed by Dr. Tarek Abichou of Florida State University (Abichou et al., 2010), demonstrates that at lower methane fluxes, oxidation rates are equal to the methane loading to the soil cover. Oxidation keeps pace with flux, and the soil cover is able to oxidize all of the methane coming from below. At lower loading rates, methane oxidation is equal to 100 percent. As flux increases, the cover is not able to oxidize all of the incoming methane, and the percent oxidation falls off. Therefore, percent oxidation starts to decrease as the methane loading to the cover increases. This relationship is shown clearly in the laboratory column studies of Rachor et al., (2011). Field studies have also confirmed this relationship between methane flux and percent oxidation (Chanton et al., 2011a,b). At low rates of methane emission, the percent oxidation is near 100 percent. As emission rates increase, the percent oxidation decreases. This analysis serves to support the approach that EPA is proposing for determining a more accurate methane oxidation fraction by calculating the methane flux rate for the landfill.
In addition to the 2012 Addendum, the landfill sector provided data for 262 private and public landfills reporting under Subpart HH. The dataset allowed the Agency to evaluate several possible options for determining more accurate methane oxidation fractions. The data conclusively showed that the average oxidation fractions for different soil cover types are all well above the default 10 percent value required by Subpart HH, and underpin the need for a revised default value or more refined method for determining an oxidation fraction at a site. WM strongly supports EPA's proposal to allow reporters to determine methane oxidation by calculating the methane flux rate on a site-specific basis.
Response:  EPA thanks the commenter for their support. See response to comment EPA-HQ-OAR-2012-0934-0041-A1, Excerpt 15.
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Commenter Name:  Michael E. Van Brunt, Director, Sustainability
Commenter Affiliation:  Covanta Energy Corporation
Document Control Number:  EPA-HQ-OAR-2012-0934-0082-A2
Comment Excerpt Number:  6
Comment:  The Rule's current defaults allow landfills to assume collection efficiencies of up to 95% and then apply a soil oxidation factor of 10%. The EPA is now proposing to increase the soil oxidation factor up to 35% in certain circumstances. In stark contrast, the U.S. EPA's own Office of Research and Development, after a multi‐site two‐year study of measured methane emissions from landfills found that "the data collected does not support the use of collection efficiency values of 90% or greater as has been published in other studies." [Footnote: U.S. EPA (2012) Quantifying Methane Abatement Efficiency at Three Municipal Solid Waste Landfills. http://www.epa.gov/nrmrl/pubs/600r12003.html] Instead, the recent EPA Report found total abatement efficiencies of 38-88%, including the effects of soil oxidation of methane in landfill cover soils. The effects of soil oxidation are inherently covered, because the EPA study looked at methane concentrations above the landfill surface. This technique cannot distinguish between methane not emitted and methane oxidized in cover soils.
Since the abatement efficiencies published in the EPA Report consider the effects of soil oxidation, higher assumed soil oxidation rates, as the EPA has proposed, would require lower collection efficiency defaults in order to remain consistent with the EPA's own work (Table 1)
[See Docket Id. No. EPA-HQ-OAR-2012-0934-0082-A2 for Table 1.]
The EPA's research has been further validated by a recent team of NOAA and university scientists. [Footnote:  Peischl, P. et al. (2013) using light alkanes in the Los Angeles basin, California.http://onlinelibrary.wiley.com/doi/10.1002/jgrd.50413/abstract] The team, looking for the sources of excess methane emissions in the Los Angeles basin validated the California Air Resources Board (CARB) inventory approach which relies on a default collection efficiency for active collection systems of 75%. In particular, based on the measurements taken, emissions from the Puente Hills Landfill were estimated 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, the overall abatement efficiency inclusive of the effects of soil oxidation is 74.7%, for a landfill with a final cover over 83% of the landfill surface. [Footnote: 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 35[th] Annual Landfill Gas Symposium Proceedings.] Assuming the newly proposed soil oxidation values of 10%, 25%, and 35%, the resultant collection efficiency at the Puente Hills landfill is 73%, 69%, and 66% respectively. Again, when looking at the actual measured emissions of methane from a landfill, assumed higher soil oxidation rates must correspond with correspondingly lower collection efficiencies. Given that new data are available, notably from the EPA and NOAA, we urge the EPA to revisit its landfill methane calculation. In particular, default collection efficiencies must be lowered to reflect the agency's own data, NOAA's data and the higher assumed rates of soil oxidation.
Response:  We have reviewed the reports and articles referenced by the commenters as well as the CARB landfill model inventory tool. With respect to the 2012 EPA landfill study, the EPA study generally appears to support the landfill collection efficiencies in Subpart HH, although it is difficult to make definitive conclusions given only three sites were evaluated and the coverage of the landfill gas collection system were not well-documented. The study looked at two sites with an intermediate cover. One of these sites averaged 70 and 77 percent recovery over two different seasons of testing, which agrees well with the default of 75 percent in Table HH-3 to subpart HH. Given the measured surface flux, the 25% oxidation factor would likely apply. Even when accounting for soil oxidation, the efficiency for this landfill's gas collection efficiency would be 69 percent, which still agrees well with the default 75 percent collection efficiency. The other site with an intermediate cover averaged 38 percent recovery, however, the report notes that the landfill gas collection system did not cover all areas of the landfill. Specifically, the west side and flat top areas of the landfill did not have any gas collection wells at the time of the study (the site upgraded its gas collection system a few months after the measurement study was completed). Assuming approximately half the landfill area was covered by the existing recovery system at the time of the testing, the gas collection efficiency estimated using the area weighting procedures outlined in Table HH-3 to subpart HH would yield an overall gas collection efficiency of 37.5 percent, again agreeing well with the measurement data. Even when using 25 percent oxidation factor (which would apply based on the measured flux rates), the subpart HH methodology would do a much better job at predicting the actual emissions from this landfill than when the CARB default assumption is used. The CARB model assumes that all landfills with gas collection systems achieve an overall gas collection efficiency of 75 percent regardless of the coverage of the landfill gas collection system. In the case of this landfill, the area weighted average gas collection efficiency used for subpart HH provides a much more realistic estimate of the overall collection efficiency for landfills that do not have a gas collection system that covers all of the landfill.
The third landfill in the study had a final cover and was projected to achieve 73 percent and 88 percent recovery during two different seasons. If the landfill's gas collection system is sufficient to cover 100 percent of the landfill area, Table HH-3 to subpart HH would suggest a default of 95 percent; if the coverage is less than 100 percent, then a lower recovery efficiency would be calculated using the area weighted procedures. While the report concluded that "The data collected does not support the use of collection efficiency values of 90 percent or greater as has been published in other studies," the report notes that other studies have shown high collection efficiencies, and a study of a single landfill is not sufficient to revise this default factor. Furthermore, it is unclear from the data presented whether the gas collection system was sufficient to cover 100 percent of the landfill area. If only 85 to 90 percent of the landfill was "under active gas collection," then the subpart HH area-weighted method would accurately account for the gas collection efficiency for this landfill (even when accounting for the 25% soil oxidation factor, which again appears to apply). The report notes that there were days of very low emission fluxes and other days of significantly higher fluxes. The investigators hypothesized that the higher fluxes may have been due to a hot spot of emissions that may not have been included in the scan areas for the other days. This hot spot could have been caused by an area of the landfill that was "not under active gas collection," for which the subpart HH methodology would reduce the overall gas collection efficiency to much less than 90 percent. If the hot spot was caused by a crack or fissure in the final cover, data for one landfill is not sufficient to conclude that all landfills with final covers have this type of "failure." For days when this hot-spot was not observed, the gas collection efficiency was on the order of 95 percent. Thus, it is reasonable to project in light of other studies that have been conducted, that landfills with properly designed and operated gas collection systems and final cover systems can achieve gas collection efficiencies of approximately 95 percent. Based on our review of the 2012 EPA study, we conclude that the results generally appear to confirm the default gas collection efficiencies in subpart HH, while highlighting the importance of the area weighted approach in Table HH-3 to reduce the overall gas collection system efficiency for areas of the landfill that are not under active gas collection.
It is unclear how different the emissions would be if the subpart HH method, with its tiered gas collection efficiency scale based on cover type and its area-weighting (to account for areas not under active gas collection as well as different cover type collection efficiencies), were used in-place of the straight 75 percent collection efficiency used by CARB. As noted in the discussion above, there are instances where the subpart HH method would provide a much better estimate of the collection efficiency (in cases of partial coverage of the gas collection system) than the CARB method. For some landfills, it would provide a lower collection efficiency estimate; for some landfills, it would provide identical collection efficiency estimates; and for other landfills, it would produce a higher collection efficiency estimate. Over a large number of landfills, it is expected that the two approaches would likely yield very similar emission estimates.
Overall, we do not see a significant difference between the subpart HH and CARB models used to estimate methane generation. Both models use the first order decay model with nearly identical default parameters. The %ANDOC value used in the CARB model is simply the product of DOC*DOCF in Equation HH-1. While the CARB model has a range of compositional profiles that it uses for wastes (data that are generally not measurable by landfill owners or operators), the overall %ANDOC value across wastes ranges from 7.5% to 11.6% in California and from 10.3% to 11.6% for other states depending on the time of disposal. The bulk waste DOC value and default DOCF value in subpart HH yield a %ANDOC value of 10%, which agrees well with the effective defaults used in the CARB model. The CARB model has similar defaults for time delay and decay rate (k-values). While subpart HH provides a tiered approach for gas collection efficiencies and has proposed to use a tired approach for oxidation factors, these changes are most significant at the individual landfill level, and are expected to be less significant when aggregating the emissions across a significant number of landfills. Thus, we consider the NOAA study that concludes that the CARB inventory is accurate across all landfills in the study area also lends credibility to the modeling approach and default parameters used in subpart HH due to the vast similarities of these two inventory methods.
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Commenter Name:  David Biderman, General Counsel, Vice President (VP), Government Affairs
Commenter Affiliation:  National Solid Wastes Management Association (NSWMA)
Document Control Number:  EPA-HQ-OAR-2012-0934-0053-A2
Comment Excerpt Number:  2
Comment:  NSWMA supports replacing the current default methane oxidation value at MSW landfills with a determination based on site-specific data. The proposal to replace the default methane oxidation fraction of 10 percent with a more refined calculation, using site-specific data, will improve the accuracy of landfill emissions estimates. EPA's proposal is supported by recent studies that have demonstrated that the fraction of methane oxidized varies depending on soil type and landfill cover. See, e.g., Chanton, J.P., Methane Oxidation in Landfill Cover Soils, is a 10% Default Value Reasonable? Journal of Environmental Quality, 38:654-663. In its comments on this proposed tiered methane oxidation factor, Waste Management (WM) refers to a white paper issued by the Solid Waste Industry for Climate Solutions (SWICS), a 2011 issue of Waste Management journal devoted to landfill gas emission issues, a November 2012 addendum to SWICS's white paper, and other studies, which support and provide a reasonable basis for EPA's proposed revision. NSWMA incorporates by reference WM's comments in support of replacing the current default methane oxidation factor with the tiered approach proposed by EPA.
Response:  EPA thanks the commenter for their support. See response to comment EPA-HQ-OAR-2012-0934-0041-A1, Excerpt 15.
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Commenter Name:  Niki Wuestenberg, Manager, Air Compliance,
Commenter Affiliation:  Republic Services, Inc.
Document Control Number:  EPA-HQ-OAR-2012-0934-0057-A1
Comment Excerpt Number:  13
Comment:  Republic supports the methane oxidation revisions as proposed in Table HH-4. The proposed methane oxidation fraction is determined based on a site-specific methane flux "bin." The "binned" approach takes into account new research in the area of methane oxidation and will improve the accuracy of landfill emission estimates. Republic values EPA's commitment to assess available data to improve soil oxidation estimates by reviewing test data not previously available and/or analyzed when the GHGRP rule was finalized in 2009. The previous data used to determine the default oxidation factor of 10% was outdated and was developed from a single study at one landfill with no gas migration controls and areas of exposed waste (Czepiel et. al). It was appropriate for EPA to recognize additional data and incorporate such into the technical correction to provide greater accuracy.
Response:  EPA thanks the commenter for their support. See response to comment EPA-HQ-OAR-2012-0934-0041-A1, Excerpt 15.
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Commenter Name:  John Skinner, Executive Director and CEO
Commenter Affiliation:  Solid Waste Association of North America (SWANA)
Document Control Number:  EPA-HQ-OAR-2012-0934-0067-A1
Comment Excerpt Number:  10
Comment:  We strongly support revision to the methane oxidation factor that will use site specific data to better estimate the landfill cover oxidation. A significant number of scientific studies have been performed in support of this revision.
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Response:  EPA thanks the commenter for their support. See response to comment EPA-HQ-OAR-2012-0934-0041-A1, Excerpt 15.
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Commenter Name:  Angela D. Marconi, Cherry Island Landfill Gas Manager
Commenter Affiliation:  Delaware Solid Waste Authority (DSWA)
Document Control Number:  EPA-HQ-OAR-2012-0934-0077-A2
Comment Excerpt Number:  6
Comment:  DSWA is pleased that EPA has proposed a revision to the methane oxidation factor that will use site specific data to better estimate the oxidation present. DSWA has previously submitted comments to EPA requesting that the methane oxidation factor be revised to reflect research that has shown the 10% default to be a poor representation of field conditions (Czepiel et. al1). The 10% factor was developed from a single study at a landfill with no gas migration controls and areas of exposed waste.
DSWA appreciates EPA's commitment to investigating the available research, including a variety of published research and the Solid Waste Industry for Climate Change Solutions (SWICS) white papers, and willingness to acknowledge the need for a revision of this factor. DSWA supports the suggested "binned" approach that has been proposed although we believe that methane oxidation is typically higher than the binned approach will reflect. We encourage EPA to remain open to new research findings and pursue revisions to the rule as needed to make the reported values as accurate as possible.
Response:  EPA thanks the commenter for their support. See response to comment EPA-HQ-OAR-2012-0934-0041-A1, Excerpt 15.
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Commenter Name:  Jami Aggers, R.E.H.S., M.A., Director
Commenter Affiliation:  Stanislaus County, CA., Environmental Resources Department
Document Control Number:  EPA-HQ-OAR-2012-0934-0038
Comment Excerpt Number:  7
Comment:  The County is pleased that the EPA has proposed a revision to the methane oxidation factor that will use site specific data to better estimate the oxidation present. The 10% factor was developed from a single study at a landfill with no gas migration controls and areas of exposed waste. It was also outdated and not reflective of the extensive new research in the area of methane oxidation.
The County appreciates EPA's commitment to investigating the available research, including various published research and the Solid Waste Industry for Climate Change Solutions (SWICS) white papers, and willingness to acknowledge the need for a revision of this factor. The County supports the suggested "binned" approach that has been proposed.
Response:  EPA thanks the commenter for their support. See response to comment EPA-HQ-OAR-2012-0934-0041-A1, Excerpt 15.
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Commenter Name:  Peter Anderson, Executive Director
Commenter Affiliation:  Center for a Competitive Waste Industry
Document Control Number:  EPA-HQ-OAR-2012-0934-0107
Comment Excerpt Number:  7
Comment:  The current rule sets a default value for methane oxidation through the landfill cover in all cases at 10% of modeled estimates of gas generated, but not captured in the active gas collection system. [Footnote: 40 CFR §98.346 (Eq. HH-5).] The proposed rule makes 10% the lower bound value for assumed oxidation, and increases that value to 25% if estimated methane fluxes through the cover are "moderate" (i.e. 10 to 70 grams/m2/day), and 35% if those fluxes are estimated to be "low" (i.e. less than 10 grams/m2/day). [Footnote: 40 CFR §98.346 (Table HH-4).]
All of this is wrong. The proposed rule's contemplation bears no relation to the known ways that landfills work, and do not work. In fact, as detailed below, landfills with so-called oxidizing covers release on a net basis substantially (e.g., greater GHG emissions than landfills designed with conforming composite covers (i.e. 60 mill HDPE and not less than 2 feet of compacted soil with permeability of <10-7 cm/sec). [Footnote: 40 CFR §258.60(a).]
No oxidation with composite covers. As the notice partially recognizes [Footnote: 78 FED. REG. 63 (April 2, 2013), at 19825], and as was clearly established from the first published study on oxidation  -  although ignored in much of the presentment by the landfill industry  -  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. At a landfill with a composite cover, gas only escapes through the geomembrane via cracks and fissures in high fluxes that exceed the capacity of microbes to oxidize, or through alternative routes such as via the leachate collection system where no oxidation occurs. [Footnote: P. M. Czepiel, "Quantifying the effect of oxidation on landfill methane emissions," Journal of Geophysical Research (July, 20, 1996)., at p. 16,720.]
No effective gas collection without geomembrane seal. Critically, however, the drafter's of the proposed rule do not appear to understand that absent an effective seal, which only that geomembrane can provide, the vacuum-based gas collection systems are only marginally functional. For without an effective seal on top, efforts to draw out the gas surrounding the collection pipes with the negative pressures created by the vacuum based system will also pull air from the surface. [Footnote: Debra Reinhart, First Order Kinetic Gas Generation Model Parameters for Wet Landfills (EPA-600/R-05/072)(June 2005), at p. 3-2; Susan Thornloe (EPA/NRMRL), Innovative Air Monitoring at Landfills Using Optical Remote Sensing with Radial Plume Mapping (February 22, 2007), at 4; and AP-42 (2008), at p. 75]  When oxygen infiltrates the waste mass from the surface at levels more than 5% (but less than 20%) in the landfill gas, the rules require the operator to damp down the system until oxygen levels recede below that 5% limit in order to avoid explosive conditions that can start an underground landfill fire. [Footnote: 40 CFR §60.753(c).]
That is to say, in order to have an effective oxidizing cover, the landfill must sacrifice significant collection capacity in the active gas system. How significant? The available field data using vertical radial plume mapping suggests almost a 300% difference. A recent study by employees of Waste Management at order to have an effective oxidizing cover, the landfill must sacrifice significant collection capacity in the active gas system. How significant? The available field data using vertical radial plume mapping the facilities it selected (and, which, therefore, one may assume reflect the best case) shows that the average methane flux at landfills with a relatively impermeable and carefully maintained geomembrane was 0.1 g CH4/m[2]/day on average, while landfills with final covers akin to oxidizing covers, but no geomembrane, were 26.61 g CH4/m[2] /day on average, 266 times higher, as shown in the FIGURE from the study replicated below. [Footnote: Douglas Goldsmith, "Methane emissions from 20 landfill across the United States using vertical radial plume mapping," Journal of the Air & Waste Management Association, 62:183-197, at p. 195 FIGURE 12 (2012)(Goldsmith Study).] Notwithstanding oxidation's enormous deficit in the real world, in the artificial universe of flawed modeling Equation HH-5 would grossly distort the actual situation by pretending oxidizing covers were more effective.
The only technically accurate support for oxidizing or bio-covers is for closed sites, typically in the undeveloped world, where the installation of active gas collection is not feasible.
[See Docket Id. No. EPA-HQ-OAR-2012-0934-0107 for FIGURE]
Parenthetically, these results, it should be noted, also make a mockery of the SWICS collection efficiency claims that industry submitted and, without notice or opportunity for comment by anyone else, EPA adopted. [Footnote: 40 CFR §98.346 (Table HH-3).] It is not credible for EPA to continue to maintain that the use of a soil-only intermediate cover only loses 21% in collection efficiency (i.e. from 95% to 75%) when the methane flux increases by 266x? We respectfully request that the issue of default gas collection efficiencies as a function of different landfill conditions be opened up for public comment, as it should have, but unlawfully was not, in the original rule promulgation in 2009.
Response:  First, we agree that landfills that do not have a soil cover (i.e., only a geomembrane cover) will not have soil oxidation. We have clarified in Table HH-4 that the proposed oxidation factors apply to landfills that have a minimum of 24 inches soil cover. Owners or operators of landfills that have a geomembrane cover with no soil cover or a soil cover less than 12 inches in depth the must use OX = 0. See Section II.R.2 of the preamble to the final rule for additional information.
With respect to the comment that there is no effective gas collection system without a geomembrane seal, we do not believe this conclusion can be reached based on the information presented in the cited study (Goldsmith, et al., "Methane emissions from 20 landfill across the United States using vertical radial plume mapping," Journal of the Air & Waste Management Association, 62:183-197). The article provides no real information about the landfills beyond the average temperature, precipitation rate, and cover type). There is no indication regarding the age of the landfills, the waste depth, or the presence (or coverage) of landfill gas collection systems, all of which could significantly impact the methane flux from the landfills studied. In fact, the only landfill that was described at all was the "closed, synthetically capped landfill covered with soil and vegetation with a gas collection system..." The low methane flux from this landfill can be attributed to the high collection efficiency of the gas collection system as expected from the default collection efficiencies in Table HH-3 and the expected higher oxidation factor expected for a soil covered landfill with low methane flux rates. Also, this landfill is closed. The timing of the closure is not specified, but methane flux rates are expected to decline after landfill closures. The studies primary focus was on validating EPA OTM-10 for use on landfills, and grouping of landfills based on cover type and climate type indicated that "...climate plays an important role in landfill methane emissions, as does cover type." The observations in the Goldsmith study appear to confirm the default gas collection system efficiencies (if these landfills had gas collection systems) and the tiered decay rate defaults based on precipitation rates included in subpart HH. We see no evidence from the Goldsmith study to indicate that the proposed oxidation factors are not appropriate.
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Commenter Name:  Peter Anderson, Executive Director
Commenter Affiliation:  Center for a Competitive Waste Industry
Document Control Number:  EPA-HQ-OAR-2012-0934-0107
Comment Excerpt Number:  8
Comment:  The hearing notice and supporting documents states that the methodological support for the proposed rule is contained in a 2012 Addendum to an earlier report by a waste industry group, Solid Waste Industry for Climate Solutions (SWICS)[Footnote: SWICS, Current MSW Industry Position and State-of-the-Practice on LFG Collection Efficiency, Methane Oxidation, and Carbon Sequestration in Landfills (2008).], which has not been provided in the rulemaking source file. The critique that follows is predicated on the assumption that the Addendum follows the work of Chanton. [Footnote: Jeffrey Chanton, "Landfill Methane Oxidation Across Climate Types in the U.S.," Env. Sci. & Tech. 45:313-319 (2011)(Canton Study).]
Of paramount concern, of course, continues to be the controlling fact that the entire oxidation case ignores the reality that the minor gains claimed are dwarfed by the enormous increase in gas that escapes since gas collection is ineffectual without a geomembrane, as shown by Waste Management's own study referred to earlier. [Footnote: Goldsmith Study.] The gains are relatively minor because even 35% oxidation only applies to the 5% or 25% of the gas generation that is not captured. The single most effective way to reduce fugitive emissions has nothing to do with oxidation, but with the installation of a composite cover, including a geomembrane, which defeats oxidation. Also, there is the problem of relying upon hothouse tests of a strategy that, its proponents concede, depends upon careful control of cover porosity, microbes and temperature, when nothing has been put forward to show that these ideal conditions will be achieved in the real world. Unless, that is, global warming is suggested will eliminate the problem of frigid winter conditions in temperate and continental climate zones.
But, putting all of that aside, the standard industry methodology for measuring oxidation, in those hothouse conditions that ignore those far larger losses, is also flawed. Canton estimated oxidation by comparing the methane concentration in the gas collected in the pipes below the surface to that in the flux chambers at the surface. But, Canton's landfill sample was weighted to sites that recover energy. [Footnote: Canton Study, at pp. 312 to 315.] Landfill-gas-to-energy (LFGTE) operators actively "tune" the collection system to boost Btu values to commercially exploitable levels by clustering the wells at the site's core, by dampening negative pressures when too much oxygen is drawn in and by rotating fields off to recover moisture. [Footnote: Debra Reinhart and Morton Barlaz, Landfill Gas Management: A Roadmap for EREF Directed Research (N.C. St. University, 2010), at p. 5.] Consequently, the methane in those pipes is artificially augmented to maximize the gas's value to LFGTE in a way that will not be observed in an equally distributed array of flux boxes across the entire surface. That inflated denominator boosts the delta values that Canton observed due to factors unrelated to oxidation.
Response:  As noted in our response to comment EPA-HQ-OAR-2012-0934-0107, excerpt 7, one cannot conclude from the Goldsmith study that landfill gas collection is ineffectual without a geomembrane cover. Subpart HH includes a tiered approach for landfill gas collection efficiencies that help to account for different collection efficiencies for different cover types. The fact that the oxidation fraction only impacts a potentially small portion of the generated landfill gas when effective landfill gas collection systems are used has little bearing to the appropriateness of the proposed oxidation fractions.
With respect to the methodology used to assess the oxidation fraction, first, we reject the categorization that the studies were done under "hothouse conditions." Many of the studies were performed across different time periods to determine an average oxidation fraction; several studies conducted during cold temperatures yielded oxidation fractions significantly greater than the previous default of 0.10. It appears the discussion regarding LFGTE operators only serves to contradict the commenter's assertion that landfill gas collection is ineffectual without a geomembrane cover. Nevertheless, it is precisely the methane generated within the landfill, well below the surface, that needs to be measured and a properly tuned gas collection system appears to be precisely what is needed to make the required internal landfill gas methane measurement. We would have preferred to have more "full-plume" tests, which would better characterize the oxidation fraction over the entire landfill area, but the surface and flux chamber measurements are not biased provided the surface locations are randomly selected and a sufficient number of measurements are made. We agree that the oxidation study data are heavily weighted to landfills with gas collection systems, which is why we do not support the average oxidation fractions by soil type presented in the summary table of the SWICS addendum. We note that all but one of the average oxidation fractions by soil type presented in the summary table of the SWICS addendum are greater than the 0.35 oxidation fraction proposed for landfills with "low flux rates" and all of them are higher than the 0.25 oxidation fraction proposed for landfills with "medium flux rates." By binning the oxidation data based on the methane flux rate (prior to any oxidation), we avoid the obvious bias in the average oxidation fractions as recommended in the SWICS addendum caused by the preponderance of studies conducted at landfills with gas collection systems. We see no reason to revise the proposed oxidation fractions binned by methane flux rates based on these comments, although we agree that the use of the binned oxidation fractions should be limited to landfills with final soil covers over most of the landfill area that contains waste. See Section II.R.2 of the preamble to the final rule regarding the use of site-specific oxidation factors in the final rule.
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Commenter Name:  Peter Anderson, Executive Director
Commenter Affiliation:  Center for a Competitive Waste Industry
Document Control Number:  EPA-HQ-OAR-2012-0934-0107
Comment Excerpt Number:  9
Comment:  EPA states that the degree of oxidation that can be used to calculate estimates of GHG emissions varies among 10%, 25% and 35%, as a function of the extent of the methane flux through the landfill cover. [Footnote: 78 Fed. Reg., 63 (April 2, 2013), at 19825, and proposed 40 CFR§98.346 (Table HH-4).]
In order to determine methane fluxes, calculations are specified, not field analysis. Those calculations rely upon the first order decay (FOD) model. [Footnote: Proposed 40 CFR §98.346 (Table HH-4, footnote a, and Eq. HH-6, Eq. HH-7 and Eq. HH-8).] For the reasons detailed elsewhere in this Comment, the model, as it is currently employed without a variable value for k to reflect different conditions, is not accurate.
Because any gains from oxidation are dwarfed by the losses attendant upon a permeable cover, the quest to adjust for different moisture levels, and k values in FOD should be the focus instead. This is what we propose to correct for the fundamental flaws in the particular design of the FOD model currently used for MSW landfills.
Response:  Direct methane flux measurements from landfills using EPA OTM-10, for example, is not practical because it is a relatively expensive test method and it can only be performed under specific conditions for selected time intervals. Therefore, we proposed to use the methane flux estimated from either the FOD model or the measured landfill gas recovery rates, depending on the equation for which OX will be used. We note that the model does have a variable value of k based on precipitation rates. We find no reason to revise the proposed oxidation fractions binned by methane flux rates based on these comments.
Revisions to other calculations methods in Equations HH-6 through HH-8
Commenter Name:  Kerry Kelly, Director, Federal Public & Regulatory Affairs
Commenter Affiliation:  Waste Management (WM)
Document Control Number:  EPA-HQ-OAR-2012-0934-0041-A1
Comment Excerpt Number:  19
Comment:  The Agency should Remove References to "Back-up Flare or Similar Device" from the Definition of fDest, n.
The proposed revised definition of fDest,n for Equations HH-6 and HH-8 includes a special provision when gas is destroyed in a "back-up flare (or similar device)." This distinction is an artifact of the original rule and is no longer necessary because the proposed revisions to HH-6 and HH-8 properly account for multiple control devices regardless of the amount of time any given control device operates during the year, or whether it is considered a primary or backup device. WM recommends simply deleting "is destroyed in a back-up flare (or similar device) or if the gas is" from the definition of fDest,n.
Response:  We agree with the commenter. Because Equations HH-6 and HH-8 have been generalized to directly account for on-site back-up destruction devices, the default of fDest = 1 is no longer necessary for back-up flares in the definition of fDest,n. The phrase requested to be deleted has been removed from the definition of fDest,n in today's final rule.
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Commenter Name:  Jami Aggers, R.E.H.S., M.A., Director
Commenter Affiliation:  Stanislaus County, CA., Environmental Resources Department
Document Control Number:  EPA-HQ-OAR-2012-0934-0038
Comment Excerpt Number:  9
Comment:  The County supports the revision of equations HH-6 and HH-8 into summations to accurately reflect the use of multiple destruction devices. We also suggest that the removal of reference to "backup device" and elimination of the use of fDest,n for backup devices will eliminate additional confusion.
Response:  See response to comment EPA-HQ-OAR-2012-0934-0041-A1, excerpt 19.
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Commenter Name:  John Skinner, Executive Director and CEO
Commenter Affiliation:  Solid Waste Association of North America (SWANA)
Document Control Number:  EPA-HQ-OAR-2012-0934-0067-A1
Comment Excerpt Number:  11
Comment:  References to "back-up" flare or "similar device" from the definition of fDest,n should be removed. This would simplify calculations since reporters would not need to designate back-up devices.
Response:  See response to comment EPA-HQ-OAR-2012-0934-0041-A1, excerpt 19.
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Commenter Name:  Niki Wuestenberg, Manager, Air Compliance,
Commenter Affiliation:  Republic Services, Inc.
Document Control Number:  EPA-HQ-OAR-2012-0934-0057-A1
Comment Excerpt Number:  15
Comment:  Republic supports the revision of equations HH-6 and HH-8 to accurately reflect the use of multiple destruction devices.
Response:  EPA thanks the commenter for their support.
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Commenter Name:  Angela D. Marconi, Cherry Island Landfill Gas Manager
Commenter Affiliation:  Delaware Solid Waste Authority (DSWA)
Document Control Number:  EPA-HQ-OAR-2012-0934-0077-A2
Comment Excerpt Number:  9
Comment:  DSWA supports the revision of equations HH-6 and HH-8 into summations to accurately reflect the use of multiple destruction devices. These changes are consistent with previously issued FAQ #389. We also suggest that EPA consider complete removal of all references to "backup device" to further simplify the calculations. Many facilities are equipped with multiple destruction devices including multiple "backup" flares and beneficial use projects that destroy landfill gas in offsite processes. Eliminating the special case for backup devices will reduce confusion by eliminating the need to determine which device should be considered to be the backup. There are cases when backup flares may operate for more hours (or destroy more landfill gas) than the beneficial use project however it stands to reason that the beneficial use project would always be considered the "primary" project because it operates with preference over flaring.
Response:  EPA thanks the commenter for their support. See response to comment EPA-HQ-OAR-2012-0934-0041-A1, excerpt 19.

Other comments on proposed subpart HH Technical Corrections
Commenter Name:  Anonymous public comment
Commenter Affiliation:
Document Control Number:  EPA-HQ-OAR-2012-0934-0037
Comment Excerpt Number:  2
Comment:  Footnote "a" to Table HH-4 states that the methane flux rate is the mass flow rate of methane per unit area at the bottom of the surface soil prior to any oxidation. What if there is no soil cover (i.e., only a synthetic cover is used)? Shouldn't the oxidation fraction in that case be 0?
Response:  We agree with the commenter. We have clarified in Table HH-4 that the proposed oxidation factors apply to landfills that have a minimum of 24 inches soil cover. For landfills that use a geomembrane cover with no soil cover or a soil cover less than 12 inches in depth, the owner or operators must use OX = 0.
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Commenter Name:  Anonymous public comment
Commenter Affiliation:
Document Control Number:  EPA-HQ-OAR-2012-0934-0037
Comment Excerpt Number:  1
Comment:  The proposed amendments to subpart HH include the addition of Table HH-4 with oxidation fractions. There is a typo in the header of the second column; should be oxidation fraction, not oxidation raction.
Response:  Thank you for your comment. The typographical error has been corrected in these final amendments.
Comments on Rule issues not proposed
Commenter Name:  Michael E. Van Brunt, Director, Sustainability
Commenter Affiliation:  Covanta Energy Corporation
Document Control Number:  EPA-HQ-OAR-2012-0934-0082-A2
Comment Excerpt Number:  7
Comment:  To ensure more complete GHG reporting, biogenic CO2 emissions resulting from the combustion of landfill gas in a flare must be included in the reporting program. Since landfill operators are already required to report the total volumetric flow of landfill gas collected for destruction for the reporting year in accordance with 40 CFFR 98.346(i)(1), the reporting of biogenic CO2 emissions from the combustion of landfill gas does not impose an additional burden on landfill operators, but it does result in more complete reporting. Reporting of biogenic emissions associated with the combustion of landfill gas combusted for energy recovery in an engine or turbine is already mandatory. It is then reasonable to require the reporting of biogenic CO2 emissions from the combustion of landfill gas with no beneficial use.
Response:  This comment raises an issue that was not opened in the proposed amendments, and therefore, is out of scope for this final rule.
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Commenter Name:  Donna M. Christensen,
Commenter Affiliation:  House of Representatives
Document Control Number:  EPA-HQ-OAR-2012-0934-0048-A2
Comment Excerpt Number:  1
Comment:  While the EPA is proposing several changes to its Greenhouse Gas Reporting Rule (the Rule), we ask that it also revisit the calculation of methane emissions from landfills. New information has become available regarding methane emissions from municipal solid waste landfills which indicates that the agency's current approach could be at risk of significantly underestimating landfill methane emissions.
In 2012, U.S. EPA's own Office of Research and Development released a report titled Quantifying Methane Abatement Efficiency at Three Municipal Solid Waste Landfills after a multi-site two-year study of methane emissions using state-of-the-art measurement technology. Last month, the Journal of Geophysical Research: Atmospheres released a study by a team of NOAA and university scientists which presented landfill methane emissions based on direct measurement of methane and other gases in the Las Angeles basin. The study validated an approach taken by the California Air Resources Board (CARB) to calculate landfill methane emissions, an approach significantly different than the one used in the Rule.
An accurate accounting of GHG emissions is vital, particularly for methane. Methane is a potent greenhouse gas. In 2009, NASA Goddard Institute and Columbia University scientists estimated methane to be 34 times stronger than CO2 over 100 years. Over shorter time period (i.e. 20-years), increasingly the focus of United Nations Environmental Programme and U.S. State Department efforts, methane is over 70 times more potent than CO2. In light of methane's potency, we applaud the U.S. EPA's proposal to update the Rule with the most recent methane global warming potential from the latest Intergovernmental Panel on Climate Change (IPCC) Assessment Report.
This action is an important step in the right direction. However, we urge the EPA to revisit the calculation of landfill methane emissions, considering the latest published research, including that of its own researchers. Failure to use the latest and best science impedes the ability of Congress to take the appropriate policy steps to most effectively reduce GHG emissions.
Response:  See response to comment EPA-HQ-OAR-2012-0934-0082-A2, Excerpt 6 in Section 22.3 of this document.
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Commenter Name:  Robert E. Cleaves, President and Chief Executive Officer (CEO)
Commenter Affiliation:  Biomass Power Association (BPA)
Document Control Number:  EPA-HQ-OAR-2012-0934-0055-A2
Comment Excerpt Number:  1
Comment:  The value of biomass to electricity rests, in part, on the environmental benefits we create by avoiding GHG emissions through energy conversion. If EPA fails to properly account for landfill emissions, it also fails to fully evaluate the environmental "externality" of not relying upon biomass to electricity and underestimates the environmental harm of landfilling over energy conversion through combustion.
In 2012, U.S. EPA's own Office of Research and Development released a report titled Quantifying Methane Abatement Efficiency at Three Municipal Solid Waste Landfills after a multi-site two-year study of methane emissions using state-of-the-art measurement technology. Last month, the Journal of Geophysical Research: Atmospheres released a study by a team of NOAA and university scientists which presented landfill methane emissions based on direct measurement of methane and other gases in the Las Angeles basin. The study validated an approach taken by the California Air Resources Board (CARE) to calculate landfill methane emissions, an approach significantly different than the one used in the Rule.
To reiterate, an accurate accounting of GHG emissions is important, particularly for methane. Methane is a potent greenhouse gas, the release of which is avoided through energy conversion in biomass boilers. EPA's consideration of this issue is particularly timely given the Agency's current rulemaking with respect to the regulation of biogenic emissions. The carbon lifecycle analysis of biomass combustion necessarily includes avoided GHG emissions that would otherwise occur if the material were landfilled. If the Agency fails to understand the magnitude of those emissions, it will also fail to properly evaluate the benefit of biogenic energy.
Response:  See response to comment EPA-HQ-OAR-2012-0934-0082-A2, Excerpt 6 in Section 22.3 of this document.
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Commenter Name:  Kerry Kelly, Director, Federal Public & Regulatory Affairs
Commenter Affiliation:  Waste Management (WM)
Document Control Number:  EPA-HQ-OAR-2012-0934-0041-A1
Comment Excerpt Number:  20
Comment:  The Agency Should Clarify the Rule with a Technical Correction to the Bulk MSW DOC Value in Table HH-1.
Earlier this year, EPA released a helpful Frequently Asked Question (FAQ) and response that clarified reporter's ability to use a more precise approach for choosing appropriate DOC value for various types of waste streams disposed at the facility in addition to bulk MSW (FAQ 744). The Agency clarified that sites that receive separate inert waste shipments, may use the appropriate DOC value for those waste streams listed in Table HH-1 under the "Waste composition option." At the same time, reporters may select the appropriate DOC value for bulk waste (0.2) found under the "Bulk waste option" section of Table HH-1 for shipments of bulk MSW.
We agree with the interpretation presented by this FAQ and request that the EPA formalize this FAQ response by adding the bulk waste DOC value of 0.2 to the list of various wastes under the "Waste composition option" section of the Table HH-1.
Response:  This provision is already explicitly provided for in §98.343(a)(2) and we do not see the need to include the bulk MSW parameters under the "Waste composition option" section of Table HH-1. Furthermore, this comment concerns an issue that was not opened by the proposed amendments and is out of the scope of this final rule.
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Commenter Name:  John Skinner, Executive Director and CEO
Commenter Affiliation:  Solid Waste Association of North America (SWANA)
Document Control Number:  EPA-HQ-OAR-2012-0934-0067-A1
Comment Excerpt Number:  13
Comment:  EPA should clarify the GHG MRR with a technical correction to the bulk MSW DOC value in Table HH-1, consistent with a Frequently Asked Question (FAQ 744) response. This response clarified that sites that received separate inert waste shipments may use appropriate DOC values for those waste streams listed in Table HH-1 under the "Waste composition option." The response further suggests that reporters may also select the appropriate DOC value for bulk waste (0.2) found under the "Bulk waste option" section of Table HH-1 for shipments of bulk MSW. This value should formally be added to Table HH-1.
Response:  See response to comment EPA-HQ-OAR-2012-0934-0041-A1, Excerpt 20.
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Commenter Name:  Peter Anderson, Executive Director
Commenter Affiliation:  Center for a Competitive Waste Industry
Document Control Number:  EPA-HQ-OAR-2012-0934-0107
Comment Excerpt Number:  6
Comment:  We state our objection to the process followed here by EPA. There has been a consistent pattern that this case illuminates in the agency's regulation of MSW landfills for how it selects issues to elevate for a decision. It concurs in major industry requests, and ignores more substantive citizen or other industry requests (or places them on a circuitous track with an uncertain destination).
EPA relies exclusively on the landfill industry's submittals, instead of independently evaluating the issue based upon a full spectrum of considerations, and without involving other stakeholders, including waste-to-energy, conversion technology, anaerobic digestion, recycling, composting, as well as citizens.
In some cases, such as the tiered gas capture rate by cover type, this was done completely outside the public review process, without notice and without any opportunity for anyone else to comment before the final decision was made, even to the extent of denying rehearing to provide an after-the-fact opportunity for comment. [Footnote: 40 CFR §98.346 (Table HH-3).] [Footnote: In the Matter of Mandatory Reporting of Greenhouse Gases - Final Rule for 40 EPA-HQ-OAR-2008-0508 CFR Parts 86, 87, 89, 90, 94, 98, 1033, 1039, 1042, 1045, 1048, 1051, 1054, 1065, Petition for Reconsideration (December 29, 2009).]
At other times, such as here with regard to oxidation, the industry requested changes are developed and completed in final draft form in sole reliance on the industry's submittals without any public involvement, the opportunity for which is only provided after the agency has committed to the approach. In either case, the process reflects a disturbing case of regulator capture that would appear to be fundamentally inconsistent with an agency's capacity to rely on sound science or achieve the climate objectives that have been announced by the Administration. [Footnote: President Obama 2013 State of the Union message to Congress]. Surprisingly, based upon personal experience, there were significantly more and extensive efforts to involve the public on an equal footing to the industry under the Bush Administration than there have been under this Administration.
Response:  We thank you for your comment. We make every attempt to involve stakeholders throughout the regulatory development process. When industry representatives requested monthly rather than weekly monitoring for methane concentrations, we made a detailed data request to the industry representatives to provide the weekly measurement data for all landfills with gas collection systems required to be collected under subpart HH (but for which reporting was deferred). Thus, while industry provided the data, the data, including the test methods, had to be collected based on the procedures specified by EPA. Once received, the Agency conducted their own independent analysis of the data, which was different than the data analyses originally used by industry representatives when recommending monthly monitoring. Similarly, we conducted an independent analysis of the test methods used to determine the oxidation fraction. Based on our analysis, the fractional isotope methodology provides an accurate method by which to determine the oxidation fraction. We received comments during the original April 2009 proposal that the oxidation fraction of 0.10 was too low. We rejected laboratory studies and indicated that the field studies, while varied, did not support a higher oxidation fraction, but that we would re-evaluate the default oxidation fraction when more field study data were available. Once additional field data were available, we conducted our own independent review and analysis of the data. We rejected the "average oxidation fraction by soil type" approach because most of the landfills studied had gas collection systems and, subsequently, lower methane flux rates than typical landfills without a gas collection system. We specifically proposed the binned oxidation approach to solicit input from the public. The Agency is not "committed to the approach" and could, based on comments and data submitted by the public, elect to finalize a different approach, as was the case of a tiered gas collection efficiency where public comment clearly indicated that a fixed 75 percent gas collection efficiency regardless of cover type or coverage of the gas collection system was clearly not the best approach for estimating landfill-specific emissions. We are happy to evaluate and respond to any and all public comments.
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Commenter Name:  Peter Anderson, Executive Director
Commenter Affiliation:  Center for a Competitive Waste Industry
Document Control Number:  EPA-HQ-OAR-2012-0934-0107
Comment Excerpt Number:  10
Comment:  On September 24, 2010, CCWI informed EPA of a significant technical error in Subpart HH of the GHG Reporting Rule, which had been published in 2009. We pointed out that the rule's default value for the annual decay rate ("k"), which is used in modeling emissions from landfills that recirculate leachate, was incorrect. [Footnote: E-mail from Peter Anderson (CCWI) to Paul Gunning (EPA), re GHG Report Rule Subpart HH, dated September 24, 2010.]
As background to understand these issues, the phrase "recirculating landfills" is a landfill that, except for one technique, engages in strategies to increase moisture as a means of accelerating decomposition. In addition to circulating leachate over and over, recirculating landfills delay installation of the final composite cover so that precipitation can continue to infiltrate the wastes long after the cell reaches final grade, as well as re-grade the covers of adjoining cells to capture their runoff. Recirculating landfills do not, however, add outside liquids. Landfills that do are known as "bioreactors,"[Footnote: Debra Reinhart, Landfill Bioreactor Design & Operation (Lewis Publishers, 1998).] and require special research permits. [Footnote: 40 CFR §258.28 prohibits adding outside liquids to M SW landfills, which is the regulatory impediment to widespread adoption of bioreactors, which do add outside liquids in addition to recirculate leachate. 40 CFR 258.4 authorizes exceptions from that prohibition for bioreactor landfills that comply with various research requirements.]
The key point is that, on the one hand, recirculating landfills are distinct from bioreactors, and, on the other, they generate currently substantially more landfill gas than dry tomb landfills. This is because a precondition for anaerobic decomposition, of which gas generation is a byproduct, is moisture levels in excess of 60%. Incoming wastes only contain, on average, 20% to 25% moisture. [Footnote: George Tchobanoglous, Integrated Solid Waste Management: Engineering Principles and Management Issues (McGraw-Hill, 1993), at p. 393. Others suggest that optimal range lies between 40% - 70%. Debra Reinhart, Landfill Bioreactor Design & Operation (Lewis Publishers, 1998), at p. 140.]
Others have done research suggesting full methane conversion does not proceed until moisture reaches 60%-70%. G. J. Farquhar, "Gas Production During Refuse Decomposition." 2 Water, Air and Soil Pollution  9, at pp. 483-495 (1973). See, also, 67 FED. REG. 346462 (May 23, 2002). Due to the heterogeneity of wastes buried in landfills, good field data is hard to find that quantifies how much additional moisture is found in recirculating vs. dry tomb landfills. However, subsidence, which is a reasonable proxy, has been found to be more than twice as much in recirculating landfills compared to dry tomb landfills. [Footnote: Debra Reinhart, "The Impact of Leachate Recirculation on MSW Landfill Operating Characteristics," 14 Waste Mgt & Res. 337 (1996), at 344.]
The decay rate that the rule provides for recirculating landfills is k=0.057. [Footnote: 40 CFR §98.346 (Table HH-1).] There are two fatal problems with using a k value that low. First, the rule indicates that k=0.057 is also to be used for dry tomb landfills in areas with 40 inches or more of annual precipitation, but was not calculated to be, and was never intended to reflect, the significantly greater moisture levels inside landfills that recirculate leachate, and, in consequence, experience twice the subsidence and presumably twice the gas generation. [Footnote: EPA's source of the k=0.057 value is Solid Waste Association of North America, "Comparison of Models for Predicting Landfill Methane Recovery," Publication No. GR-LG 0075 (1998), whose scope was limited to dry tomb landfills.]
Response:  This comment addresses sections of the rule that were not opened by the proposed amendments and are out of the scope of this final rule. While we will consider these comments, any revisions to the decay rate values used in subpart HH, if deemed appropriate, will have to be made in a separate rulemaking to allow for public notice and comment.
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Commenter Name:  Peter Anderson, Executive Director
Commenter Affiliation:  Center for a Competitive Waste Industry
Document Control Number:  EPA-HQ-OAR-2012-0934-0107
Comment Excerpt Number:  11
Comment:  The agency's own hornbook for input values to the first order decay model, AP-42, specifically states that the k value for landfills that recirculate leachate, which it abbreviates as "wet landfills," is 0.3,  or 5.3x greater. [Footnote: EPA, Background Information Document for Updating AP42 Section 2.4 for Estimating Emissions from Municipal Solid Waste Landfills (2008)(AP-42 Background), at p. 5. See, also, Reinhart, First Order Kinetic Gas Generation Model Parameters for Wet Landfills (EPA-600/R-05/072)(June 2005).] Elsewhere, EPA has emphasized the critical importance of maintaining consistency among other offices in the agency, such as with the GHG Inventory. [Footnote: 78 FED REG. 63 (April 2, 2013), at 19808.] It is odd that EPA is indifferent to such a very large inconsistency here in regard to its own rule book, AP-42.
Unlike most other sources of GHGs, emissions from MSW landfills are indirect sources that are not measured. Instead emissions are estimated with an equation, called the first order decay (FOD) model, one of whose key input variables is the value for k. Current gas generation calculated with the model are 3.1x greater for k=0.3 than for k=.057, when using L =100 m3/MT, for total gas potential.
The internal email traffic among EPA staff that we received in response to our Freedom of Information Act requests indicate that, first, nothing was done to correct this fundamentally incorrect value, which understates emissions in recirculating landfills by three times. [Footnote: E-mail from Dana Hyland (EPA) to Peter Anderson (CCWI), re: EPA-HQ-2013-005296, dated April 29, 2013.] Then, an effort was begun to conduct a survey of bioreactor landfills, even though, the issue was how estimate GHG emissions from leachate recirculating landfill, which do not add outside liquids, and had nothing to do with bioreactors. For there are very few bioreactors due to the increased regulatory requirements, the marginal gain in accelerating decomposition and the greater risks to site stability with elevated moisture levels. [Footnote: 40 CFR §258.4; Morton Barlaz, "Performance of North American Bioreactor Landfills. II. Chemical and Biological Characteristics," J. Env. Eng. (August 2010); and R. C. Bachus, "Bioreactor Landfill Stability: Key Considerations," MSW Management (September/October 2004), at p. 82.]
On the other hand, the increasingly predominant practice among large landfills today is leachate recirculation. [Footnote: EPA, Mandatory Greenhouse Gas Reporting Rule: EPA's Response to Public Comments, Volume No.: 36, Subpart HH --  Landfills (2009), at p. 72.] Finally, the agency spent months discussing whether "wet landfills" in AP-42 only applied to bioreactors.
AP-42 made clear that the recommended k=0.3 value was for wet landfills, which included primarily leachate recirculating landfills as well as bioreactors:
      "Due to the increase in the use of leachate recirculation, a gas production rate to characterize emissions from wet landfills has been added." [Footnote:  AP-42 Background, at p. iii.]
      "There has been an increase in the occurrence of landfills that recirculate leachate to accelerate waste decomposition. An additional `k' was added for use in the first- order equation to account for the increase in gas production from wet landfills. This was derived from a study that evaluated data from 29 wet landfills (Reinhart, 2005). For the purpose of AP-42, wet landfills are defined as landfills which add large amounts of liquid to the waste from recycled landfill leachate, condensate from LFG collection, and other sources of water such as treated wastewater." [Footnote: AP-42 Background, at p. 2.]
Finally, EPA temporized because of a concern that the AP-42 value might be too high for recirculating landfills because it included some consideration of bioreactor landfills. But, one of the studies that EPA relied upon specifically found that bioreactors do not generate appreciably more gas than leachate recirculating landfill without outside liquids:
      "There is no indication that gas collection increases appreciably when the water content reaches 40%." [Footnote: Morton Barlaz, "Performance of North American Bioreactor Landfills. II, Chemical and Biological Characteristics," J. Env. Eng. (August 2010), at p. 839, included as part of EPA Response to CCWI FOIA Request (October 25, 2012).]
EPA defines bioreactors as landfills with more than that 40% moisture level. [Footnote: EPA, Example Moisture Mass Balance Calculations for Bioreactor Landfills (EPA-456/R-03-007, December 2003), at p. 2.]
We are not oblivious to the fact that EPA may be recalcitrant to using the correct value for k because tripling reported emissions from recirculating landfills would make manifest the carefully worded warnings from the agency's own research division, and which even Waste Management's own Goldsmith Study confirms. That is, functional gas capture cannot be achieved at these facilities:
      "Alternative covers or porous materials are used to promote infiltration which results in larger loss of fugitive emissions." [Footnote: Susan Thornloe (EPA/NRMRL), "Innovative Air Monitoring at Landfills Using Optical Remote Sensing with Radial Plume Mapping" (February 22, 2007), at 4.]
Indeed, the same conclusion follows for landfills with LFGTE, because sites that recover energy also recirculate leachate in order to boost the otherwise low Btu value of landfill gas.
Response:  First, we note that the k value of 0.3 appears in a DRAFT version of AP-42 and this k value cannot be considered "EPA's own hornbook" value until such time as the AP-42 chapter is finalized. Second, the k values used in the GHGRP are consistent with the values developed for the U.S. Emissions Inventory of U.S. Greenhouse Gas Emissions and Sinks and consistent with k values recommended for bulk MSW in the 2006 IPCC Guidelines. There appears to be some confusion with the semantics of "wet landfill." The term wet landfill is not used in subpart HH. Subpart HH defines three climactic conditions based on precipitation and recirculation rates. While some may refer to landfills in moist climates as wet landfills, there is a distinction between what is considered a wet landfill as described in the draft AP-42 section and a landfill in a "wet climactic region" as indicated by greater than 40 inches of precipitation. Finally, we note that this comment addresses sections of the rule that were not opened by the proposed amendments and are out of the scope of this final rule. While we will consider these comments, any revisions to the decay rate values used in subpart HH, if deemed appropriate, will have to be made in a separate amendatory package to allow for public notice and comment.
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Commenter Name:  Peter Anderson, Executive Director
Commenter Affiliation:  Center for a Competitive Waste Industry
Document Control Number:  EPA-HQ-OAR-2012-0934-0107
Comment Excerpt Number:  12
Comment:  Again, and as noted earlier here and in regard to the original rule, there are no actual measurements of GHG emissions from landfills. Instead, modeling is used in the Mandatory Reporting of GHG Emissions in order to estimate what those emissions from MSW landfills are assumed to be. That is, the first order decay model, which has no validity in relation to landfills unless it adjusted to provide for a variable, instead of a fixed, value for k. Of note, more recently, even one of the strongest advocates of FOD modeling, Dr. Jean Bogner, has repudiated the exercise. [Footnote: Jean Bogner, California Landfill Methane Inventory Model Users Guide, at p. 2.]
As part of our comments on the original rule, we made that same point, and incorporate them here as if set forth in full. [Footnote: EPA, Mandatory Greenhouse Gas Reporting Rule: EPA's Response to Public Comments, Volume No.: 36, Subpart HH --  Landfills (2009), at p. 65.]
[Original rule comments are available at: http://www.regulations.gov/#!searchResults;rpp=25;po=0;s=EPA-HQ-OAR-2008-0508-0331;fp=true;ns=true]
In response to those comments, EPA stated that:
     (1) "[S]tatistical analysis of the data available from landfills with gas collection systems where methane composition and flow were measured provide a strong basis for the use of the first order decay model and the proposed input parameters."
     (2) "While the commenter criticizes the use of the first order decay model, the commenter does not provide any workable alternative."
[Footnote: Id., at p. 72. The response also stated that "the commenter appears focused on landfills that have geomembrane covers. While the degradation aspects for "dry tomb" waste disposal may be very different from those with soil or clay covers, we do not anticipate that these landfills will be in the majority. We do request information on soil cover type and leachate recirculation in the final rule to better understand the prevalence of these practices." Id., at p. 72. CCWI concurs that recirculating landfills are becoming dominant on a waste-weighted basis, and, to the contrary, is focused on them, not dry tomb landfills, where the predominant fraction of GHG's are coming from. Id. There was and is not confusion on CCWI's part.]
In fact, the FOD model cannot be statistically validated for MSW landfills, and there are workable adjustments to correct for the flaws in the current form of the FOD model were EPA to provide the same commitment to this vital task as it has to the industry's peripheral oxidation matter.
Attempts to statistically support FOD models was based upon a putative statistical test that used regression equations of a sample that purported to show its predictions were a good fit. The regression analysis prepared for EPA by Peer was intended to validate the FOD model's applicability to the approximately 2,000 MSW landfills in the United States, but it failed to do so. [Footnote: R. L. Peer, et al., "A comparison of methods for estimating global methane emissions from landfills," 26 CHEMOSPHERE 387 (1993).] The Peer study used too small a sample of only 21 landfills, or only 1% of the population, which is too few degrees of freedom for statistical significance. Also, none of those selected for the sample were chosen randomly, which removes the normal distribution essential for regression equations to estimate a population.
Furthermore, not only was the selection process not random, it was also chosen with a specific bias that has the effect of significantly skewing results to appear to show high capture rates. This was done by limiting the sample to landfills with energy recovery. These facilities typically recirculate leachate, which accelerates decomposition and gas generation, in order to boost the profitability of electricity sales. [Footnote: Debra Reinhart, First Order Kinetic Gas Generation Model Parameters for Wet Landfills (EPA-600/R-05/072)(June 2005), at p. 2-2.] That has been shown to increase near term gas generation very significantly, while only moderately increasing the volume of gas captured. [Footnote: Contrast: Pat Sullivan and Alexander Stege, "An Evaluation of Air and Greenhouse Gas Emissions and M ethane-Recovery Potential from Bioreactor Landfills," MSW Management (Sept 2000), at p. 78, states that bioreactor landfills increase near term gas capture per ton of waste-in-place by 76%; with 67 FED REG 36463 and 36465 (May 22, 2002): bioreactors increase gas generation in the near term by 2 to 10x.]
Since the model is blind to the fact that gas generation was augmented, the uptick in gas collected makes it seem appear that capture rates have significantly improved, even though they most probably have significantly declined.
Moreover, in addition to all those limitations, circular reasoning was used in performing the model's attempt at a statistical validation. In an attempt to assess the reasonableness of the model's estimates of Gas Generation, Eq. (1) is used to provide a putative independent estimate:
      Gas Captured = Gas Generated x Gas Capture Rate   (1)
Solving Eq. (1) for Gas Generated is Eq. (2):
      Gas Generated = Gas Captured/Gas Capture Rate     (2)
But, since only one of the two independent variables is known, this exercise rests on a house of cards. For the Gas Capture Rate is also unknown and an unsupported guesstimate is used, defeating the attempt to provide a solid foundation for the calculation. Thus, to solve the equation for Gas Generation, the study just assumed that Gas Capture Rate was 75% at all times during a landfill's life. Recalling that one of the purposes of the entire exercise was to establish a factual basis for assuming 75% capture rates in the first place, this led to a circular exercise with no statistical value. As a tautological statement, it establishes nothing about Gas Capture Rates anymore than it does about Gas Generation.
Finally, in view of the fact that moisture, which is a limiting condition for decomposition landfill decay behavior obviously reflects complex interactions, which are especially difficult to model in a heterogeneous waste mass that goes through multiple phases some of which when prerequisite moisture levels are absent. The reason given to justify the paucity of other explanatory variables in the model to explain that complex environment, such as critical internal moisture levels, is that the excluded variables had statistically insignificant estimated coefficients in earlier versions of the regressions.
But, the problem of statistically insignificant coefficient estimates arises for many reasons other than the claimed lack of importance. One of the reasons for insignificant coefficients is a small sample size that leads to limited degrees of freedom, which is evident in the study. Other problems include poorly formulated equations, data measurement errors, and inappropriate error term distribution specifications and related estimation procedures. Each of these problems exist.
This points towards an unreliable and questionable estimation process known as data mining or fishing, and not to the lack of importance of things, such as moisture, needed for a valid model. With these fishing procedures, various fuller models are formulated and discarded, not because they are not well formed or include inappropriate variables, but because the analysts did not want to confront the substantial complexities or consequences that more complete modeling would entail.
The exclusion of variables merely on the basis of low levels of estimated coefficient significance is not statistically justified, as shown by the irrational scattergun outputs it produces. For, if the excluded data are truly relevant, their exclusion leads to estimation bias and unreliable results. Coefficient significance is not an appropriate means for deleting variables from a regression model. Appropriate tests exist for testing overall significance of a set of variables  -  e.g. maximum likelihood ratio tests. The Peer paper does not show that these forms of significance testing were performed.
Due to all of the deficiencies discussed above, the results of the regression analyses cannot be relied upon to provide credible annual methane production quantities, anymore than the putative validation of the FOD model can corroborate that the model conforms to statistical norms. In addition to all of the problems discussed above, the low levels of R2s in the Peer study (one measure of the explanatory power of estimated regression equations) do not support a conclusion that the regression analyses provide reliable results.
Response:  See our response to comment EPA-HQ-OAR-2012-0934-0107, Excerpt 13.
--------------------------------------------------------------------------------

Commenter Name:  Peter Anderson, Executive Director
Commenter Affiliation:  Center for a Competitive Waste Industry
Document Control Number:  EPA-HQ-OAR-2012-0934-0107
Comment Excerpt Number:  13
Comment:  For those who find statistical discussions obscure, the uselessness of the current state of FOD modeling for the estimation of landfill emissions, there is a more straightforward proof. That is the number of studies that have tested the model by noting the gas captured at a large sample of landfills, calculating the gas capture rate using the following equation.
      Capture Rate = Gas Generated/Gas Captured (3)
A published paper that performed a random verification of related modeling of California landfills found a dispersion of 25 major landfills of predicted compared to actual values for gas collection efficiency, which ranged from 7% to 100%, which suggests an R2  value of only 0.7. [Footnote: Nickolas Themelis, "Methane generation in landfills," Renewable Energy 32 (2007), 1243, at 1250.]
A more recent unpublished survey of 30 California landfills by the California Air Resources Board, reproduced in TABLE 1 below, found implied gas collection efficiency from gas generation estimated with first order equations ranged from 6% to 225% captured, which is an exceedingly impressive engineering feat. [Footnote: California Air Resources Board, Staff Spreadsheet Titled Landfill Survey Data Public (2010).]
                                    TABLE 1
California Integrated Waste Management Board Implied Gas Capture Rate at 46 Landfills When Comparing Gas Captured with Estimates of Gas Generated from First Order Decay Model
                         Landfill Survey Response Data
                    Survey CH4 Captured/Model CH4 Generation(%)
                                    Landfill
                                    2006WIP
                                      (%)
                                    Avg. CH4
                                      (%)
                                      2000
                                      2001
                                      2002
                                      2003
                                      2004
                                      2005
                                      2006
                                        1
  9.4%
   35%
 109%
 120%
 107%
 108%
 112%
 140%
 140%
                                        2
  3.7%
   46%
  87%
 108%
 114%
 109%
 107%
 135%
 130%
                                        3
  3.2%
   52%
  61%
  63%
  73%
  68%
  52%
  51%
  83%
                                        4
  3.0%
   39%
  63%
  73%
  66%
  79%
  76%
  90%
  87%
                                        5
  2.7%
   36%
  91%
  91%
  91%
  91%
  84%
  98%
  92%
                                        6
  2.3%
   34%
 121%
 121%
 121%
 121%
 121%
 121%
 121%
                                        7
  2.2%
   42%
  99%
 105%
 109%
 111%
 105%
 107%
 104%
                                        8
  2.2%
   14%
  6%
  5%
  4%
  6%
                                       5%
                                       6%
  6%
                                        9
  1.9%
   16%
  66%
  65%
  65%
  57%
  59%
  76%
  76%
                                        10
  1.8%
   25%
 125%
 113%
 100%
  97%
 112%
 124%
 124%
                                        11
  1.8%
   50%
  64%
  69%
  71%
  69%
  66%
  63%
  63%
                                        12
  1.8%
   42%
 127%
 127%
 127%
 127%
 127%
 146%
 117%
                                        13
  1.4%
   32%
 121%
 137%
 128%
 123%
 119%
 126%
 126%
                                        14
  1.3%
   49%
 124%
 119%
 105%
 102%
 102%
  76%
  72%
                                        15
  1.3%
   50%
  59%
  51%
  41%
  54%
  54%
  54%
  54%
                                        16
  1.3%
   43%
 351%
 261%
 231%
 226%
 172%
 166%
 165%
                                        17
  1.2%
   40%
  45%
  45%
  45%
  45%
  53%
  46%
  44%
                                        18
  1.1%
   39%
 118%
 118%
 118%
 118%
 133%
 118%
 109%
                                        19
  1.1%
   47%
  78%
  54%
  96%
 103%
  90%
  90%
 116%
                                        20
  1.1%
   44%
  64%
  63%
  65%
  40%
  51%
  39%
  37%
                                        21
  0.8%
   51%
  89%
  90%
 103%
  82%
  81%
  83%
 108%
                                        22
  0.7%
   50%
  74%
  73%
  76%
  88%
  75%
  94%
 121%
                                        23
  0.6%
   48%
 152%
 180%
 140%
 109%
 104%
  96%
  91%
                                        24
  0.5%
   48%
  28%
  35%
  42%
  50%
  62%
  70%
  64%
                                        25
  0.4%
   59%
  57%
  57%
  57%
  57%
  57%
  57%
  57%
                                        26
  0.4%
   29%
  22%
  22%
  20%
  21%
  21%
  25%
  21%
                                        27
  0.4%
   48%
  23%
  23%
  23%
  23%
  15%
  21%
  34%
                                        28
  0.3%
   38%
  20%
  26%
  23%
  21%
  19%
  14%
  16%
                                        29
  0.3%
   40%
 111%
 111%
 116%
 102%
 114%
  99%
  98%
                                        30
  0.3%
   43%
 104%
 104%
 104%
 104%
 104%
  93%
 114%
                                        31
  0.3%
   37%
  29%
  29%
  29%
  30%
  33%
  28%
  25%
                                        32
  0.2%
   42%
  31%
  31%
  31%
  31%
  31%
  28%
  34%
                                        33
  0.2%
   41%
  22%
  22%
  19%
  20%
  21%
  24%
  30%
                                        34
  0.2%
   48%
 103%
  85%
  80%
  91%
 124%
 123%
 135%
                                        35
  0.2%
   17%
  6%
  6%
  5%
  6%
                                       6%
                                       6%
  6%
                                        36
  0.1%
   48%
  78%
  78%
  78%
 102%
  74%
  66%
  79%
                                        37
  0.1%
   32%
  35%
  40%
  38%
  54%
  62%
  62%
  50%
                                        38
  0.1%
   33%
  38%
  17%
  20%
  16%
  17%
  27%
  23%
                                        39
  0.1%
   38%
 257%
 257%
 341%
 234%
 234%
 216%
 257%
                                        40
  0.1%
   37%
  44%
  38%
  33%
  18%
  33%
  33%
  33%
                                        41
  0.0%
   45%
  76%
  76%
  76%
  85%
  78%
  65%
  76%
                                        42
  0.0%
   37%
  69%
  66%
  63%
  59%
  56%
  52%
  49%
                                        43
  0.0%
   30%
  46%
  41%
  37%
  32%
  27%
  23%
  19%
                                        44
  0.0%
   27%
 165%
 161%
 157%
 138%
 137%
 138%
 126%
                                        45
  0.0%
   31%
  38%
  38%
  38%
  38%
  38%
  22%
  47%
                                        46
  0.0%
   30%
  18%
  17%
  14%
  14%
  14%
  14%
  10%

Similarly, Wisconsin did a comparison of actual gas collected to estimate gas generation in the State's landfills and found the same exceedingly wide and irrational outputs for imputed collection efficiency found in California's study. [Footnote: On-line at:  http://dnr.wi.gov/topic/Landfills/emissions.html.]
Response:  We recognize that there are many the uncertainties in the FOD model, particularly the use of a nationwide average DOC value, to estimate methane generation rates for specific landfills. Differences in waste compositions from landfill to landfill are expected to cause differences in the methane generation rates on the order of those seen here. This is precisely why subpart HH requires both a forward calculation of methane generation using Equation HH-1 and HH-5 and a backward calculation method (Equation HH-7). We continue to maintain that the FOD model is reasonably accurate and that it is used and accepted worldwide for developing methane emission estimates for landfills. As noted in our response to comment EPA-HQ-OAR-2012-0934-0082-A2, Excerpt 6 in Section 22.3 of this document, the NOAA study using atmospheric measurements of methane concentrations indicated that the California emissions inventory for landfills, which is based on the use of the FOD model, was accurate. There are no changes to the rule as a result of this comment.
--------------------------------------------------------------------------------

Commenter Name:  Peter Anderson, Executive Director
Commenter Affiliation:  Center for a Competitive Waste Industry
Document Control Number:  EPA-HQ-OAR-2012-0934-0107
Comment Excerpt Number:  14
Comment:  The fact that the current FOD model has critical flaws that preclude its applicability to MSW landfills does not mean that there are no workable alternatives.
Correcting for those errors first requires developing reasonable estimates for the value of k under the different conditions of a landfills life when operated as a dry or a wet facility. Second, the model needs to be run in each year with the correct k value for the conditions that exist in that year (open/closed, type of cover, recirculation, local precipitation, etc.). Thus, when EPA copied the SWICS cover-based capture rates, in addition to using made up values, it ignored the key fact. While it is true that gas collection is substantially higher after a geomembrane is installed, gas generation quickly tapers off at that time. Most gas is generated before and afterwards when there is no effective cover and gas capture is, according to the industry's own study, 300% worse.
CCWI would welcome discussions with EPA to bring together a small team to accomplish the changes in the model to account for this "Double Dutch" jump ropes effect. EPA has done as much for the waste industry, as in the case of oxidation factors, and it could do the same for others without their sort of financial interest in the outcome that distorts the results.
In passing, optical scanning does provide useful comparative information about emissions among different landfill conditions. However, it is not yet useful for estimating landfill GHG emissions. In terms of its essential construct, and as discussed earlier, more than half of the degradable carbon remains in dry tomb landfills, and probably also close to that with recirculating landfills, when the site is closed. [Footnote: P. M. Czepiel, "Quantifying the effect of oxidation on landfill methane emissions," Journal of Geophysical Research (July, 20, 1996)., at p. 16,720.] That carbon can be expected to decompose, and generate gas that will be released, following the 30 year post closure period and the financial assurances are exhausted [Footnote: 40 CFR Part 258, Subparts F and G.] None of that is measured by optical scanning's basic construct.
The methodology also has other technical problems that make its results at this time still too subjective and variable to be reliable for current emissions, notwithstanding EPA's attempt in 2006, referred to as OTM-10, to standardize optical scanning. [Footnote: EPA, Optical Remote Sensing for Emission Characterization from Non-Point Sources (2006) (OTM -10).] For example:
      Upwind. Chief among the problems that eludes precise measurement of methane concentrations in the scanned vertical plane is the fact that gases in the atmosphere upwind of that plane mix with it. If those upwind gases that cross the plane are not accounted for and subtracted from the observed fluxes in that plane, the results will be erroneous. To distinguish the two requires first defining the boundaries of the contributing area, which defies clear delineation, and choosing from among the two published models to measure the upwind contribution, which are predicated on general regression equations derived from controlled releases of tracer gases or from computer simulations. The fact that the two produce different results raises a question about the validity of one or both of the estimation methodologies. Also, to different degrees, both models are predicated upon a simplified assumption of contributory winds crossing a flat surface, which usually does not describe the more complex and irregular landfill terrain being scanned in most cases.
      Weather variability. Unless observations are limited to days when there is no wind, which would be a costly constraint and logistical nightmare, shifting wind speed and direction, a near constant at the top of many landfills hundreds of feet above grade, make conducting reliable observations considerably more challenging and subjective, even with a four plane configuration of the optical scanners.
      Impromptu adjustments. In the field, with landfills' vast expanses, irregular terrain, high reaches and shifting winds, there is no single uniform protocol to manage all contingencies that confront the researcher, and he or she is required to make any number of subjective adjustments and compromises not set forth in OTM-10 in order to complete the necessary tasks.
      Inconsistent parameters. As previously noted, some researchers choose, or more likely are required by their host, to ignore the working face, while some, but not others, maintain that side slope measurements cannot be done. Yet, the working face is where most of the gas escapes from before closure, and afterwards, more is released off the side slopes. After the site is covered, there is a strong bias to horizontal gas migration due to daily cover and packing and the way horizontal fissures propagate with compaction. If neither the working face nor side slopes are included, the results will fail to account for the vast majority of emissions.
      Weak analogy. The computational algorithms, multiple regressions and procedures in OTM-10 were actually developed for hog lagoons, which are significantly smaller facilities than landfills on flat terrain at ground level. [Footnote: R. D. Shores, et al., "Plane-integrated open-path Fourier transform infrared spectrometry methodology for anaerobic swine lagoon emission measurements," Appl. Eng. Agric. 21:487 - 492 (2005).]  Simply scaling up from those lagoons to massive landfills extending over hundreds of acres and reaching 300 or more feet above grade, with irregular features and the complex wind patterns discussed above is, by itself, a reach, confounded further by the fact that so much of the actual study details wind up having to be fleshed out ad hoc on site without serious validation. [Footnote: The Goldsmith study concluded: "However, the fact that only 31% of the data collected fulfilled the quality assurance/ quality control (QA/QC) requirements for qualifying data is a concern. The method is at times not easy to apply to the complex topography of a landfill and there are areas of landfills that are not accessible to the technique." Id., at 196 (emphasis added).]
Response:  We thank you for your comment. We agree that it is not practical to require the use of EPA OTM-10 as a means to determine landfill emissions at this time, which is why we rely on the FOD model and landfill gas collection system measurements. We welcome comments and suggestions that would improve subpart HH's emission estimates. There are no changes to the rule as a result of this comment.
Revisions to Subpart II
No comments were received on the proposed revisions to this subpart.
Revisions to Subpart LL
No comments were received on the proposed revisions to this subpart.
Revisions to Subpart MM
Revisions to calculation methods
Commenter Name:  Karin Ritter, Manager, Regulatory and Scientific Affairs
Commenter Affiliation:  American Petroleum Institute (API)
Document Control Number:  EPA-HQ-OAR-2012-0934-0047-A2
Comment Excerpt Number:  28
Comment:  EPA is proposing to clarify the equation term for "Producti" at 40 CFR 98.393(a)(2) to exclude those products that entered the refinery but are not reported under 40 CFR 98.396(a)(2).
Minor editorial change since paragraph (1) was removed.
Response:  Yes, this is a minor editorial change. There are no changes to the rule as a result of this comment.
Revisions to equipment calibration requirements
Commenter Name:  David Friedman, Vice President, Regulatory Affairs,
Commenter Affiliation:  American Fuel & Petrochemical Manufacturers (AFPM)
Document Control Number:  EPA-HQ-OAR-2012-0934-0060-A1
Comment Excerpt Number:  5
Comment:  EPA proposes to incorporate into Subpart MM a provision similar to the equipment calibration provision in Subpart A where a calibration may be postponed for units and processes that operate continuously with infrequent outages. AFPM supports this harmonizing change to make the equipment calibration provisions for petroleum product suppliers consistent with the calibration requirements for other sectors and the flexibility it provides Subpart MM reporters.
Response:  EPA thanks the commenter for their support.
Revisions to reporting requirements
Commenter Name:  Marla Benyshek, Director, Fuels Regulatory Issues
Commenter Affiliation:  Phillips 66 Research Center
Document Control Number:  EPA-HQ-OAR-2012-0934-0046-A1
Comment Excerpt Number:  1
Comment:  We are very appreciative of the proposed change that eliminates the detailed crude reporting requirements. The existing reporting requirement is burdensome. Some of our refineries have had to institute additional sampling and testing to be able to provide the crude reporting information in the required manner. For all refineries additional time and effort is required to match crude names with EIA codes and ensure the batch information is complete and accurate. We have consistently voiced our objection to any requirement for crude reporting in this regulation. Although the proposal does eliminate the most burdensome portion of the required crude reporting, we again request that EPA completely eliminate any crude oil reporting requirement rather than just change it to reporting of annual quantity.
Response:  EPA collects data on the volume of crude oil to conduct a mass balance assessment of all feedstocks, onsite emissions, and outgoing products at a refinery to assist with quality assurance and verification of data reported under subpart MM. Therefore, the EPA will not be completely eliminating crude oil reporting in this rulemaking.

--------------------------------------------------------------------------------

Commenter Name:  Marla Benyshek, Director, Fuels Regulatory Issues
Commenter Affiliation:  Phillips 66 Research Center
Document Control Number:  EPA-HQ-OAR-2012-0934-0046-A1
Comment Excerpt Number:  2
Comment:  Reporting Product Volumes by Measurement Method. EPA is proposing to eliminate the required reporting by measurement method. Phillips 66 strongly supports this change as it will simplify the reporting requirements.
Reporting Measurement Methods. Although the Agency has proposed to eliminate reporting of product volumes by measurement methods, there still remains a requirement to report a list of methods used to measure the annual product quantities reported. Phillips 66 believes that this reporting requirement should also be eliminated as it is tangential to the GHG emissions data and information that EPA is seeking.
Response:  Please see Section II.T.2 in the preamble to the final rule for EPA's response to this comment.
--------------------------------------------------------------------------------

Commenter Name:  Karin Ritter, Manager, Regulatory and Scientific Affairs
Commenter Affiliation:  American Petroleum Institute (API)
Document Control Number:  EPA-HQ-OAR-2012-0934-0047-A2
Comment Excerpt Number:  32
Comment:  EPA is proposing to remove the requirements of 40 CFR 98.396(a)(1), (a)(5), (a)(13), (b)(1), and (c)(1) for each facility, importer, and exporter to report the annual quantity of each petroleum product or natural gas liquid on the basis of the measurement method used. Reporters would continue to report the annual quantities of each petroleum product or natural gas liquid in metric tons or barrels at 40 CFR 98.396(a)(2), (a)(6), (a)(14), (b)(2), and (c)(2). EPA is also retaining the requirement to report a complete list of methods used to measure the annual quantities reported for each product or natural gas liquid.
API supports the simplification associated with this revision.
Response:  EPA thanks the commenter for their support.
--------------------------------------------------------------------------------

Commenter Name:  Karin Ritter, Manager, Regulatory and Scientific Affairs
Commenter Affiliation:  American Petroleum Institute (API)
Document Control Number:  EPA-HQ-OAR-2012-0934-0047-A2
Comment Excerpt Number:  33
Comment:  EPA is proposing to eliminate the reporting requirement for individual batches of crude oil feedstocks. The reporting requirements for crude oil at 40 CFR 98.396(a)(20) are proposed to be changed to require only the annual quantity of crude oil. EPA is also proposing to eliminate the requirement to measure the API gravity and the sulfur content of each batch of crude oil at 40 CFR 98.394(d). EPA is also proposing to remove the requirement at 40 CFR 98.394(a)(1) that a standard method by a consensus-based standards organization be used to measure crude oil on site at a refinery, if such a method exists. Other associated changes to the rule to harmonize with this change include removing the definition of "batch," removing the procedures for estimating missing data for determination of API gravity and sulfur content at 40 CFR 98.395(c), and the recordkeeping requirement for crude oil quantities at 40 CFR 98.397(b). Reporters would still be required to maintain all the records required to support information contained in the reports as specified at 40 CFR 98.397(a).
API had commented during the initial rule developments in 2009 that refiners should not be required to provide data for each batch of crude used at the refinery. The data are not used to calculate GHG emissions from products under Subpart MM, and could not be used to determine carbon emissions from the refinery, and should therefore not be required. Additionally, the information is publically available through EIA form 814. API strongly supports these revisions.
Response:  EPA thanks the commenter for their support.
--------------------------------------------------------------------------------

Commenter Name:  David Friedman, Vice President, Regulatory Affairs,
Commenter Affiliation:  American Fuel & Petrochemical Manufacturers (AFPM)
Document Control Number:  EPA-HQ-OAR-2012-0934-0060-A1
Comment Excerpt Number:  7
Comment:  EPA proposes to eliminate several crude oil reporting requirements in Subpart MM for petroleum refineries. This includes eliminating the requirement to report EIA crude stream code and crude stream name, API gravity, and sulfur content of each crude oil that enters the refinery. Other associated changes to Subpart MM to harmonize with these eliminations including removing the provisions around API gravity and sulfur content measurement and removing the requirement that a standard method by a consensus-based standards organization be used to measure crude oil on site at a refinery. EPA explains that refineries would no longer report crude oil by batch, but would still report the annual quantity of crude oil that enters the refinery. AFPM supports the changes to crude oil reporting as proposed. Crude oil names, API gravity and sulfur content are not used in calculating GHG emissions and are publicly availability via the Energy Information Administration.
Response:  EPA thanks the commenter for their support.
--------------------------------------------------------------------------------

Commenter Name:  David Friedman, Vice President, Regulatory Affairs,
Commenter Affiliation:  American Fuel & Petrochemical Manufacturers (AFPM)
Document Control Number:  EPA-HQ-OAR-2012-0934-0060-A1
Comment Excerpt Number:  6
Comment:  EPA proposes to remove the requirement for Subpart MM reporters to report the annual quantities of each petroleum product or natural gas liquids (NGL) on the basis of the measurement method used. EPA further explains that reporters would continue to report the annual quantities of each petroleum product or NGL and a complete list of the methods used to measure the annual quantities for each product or NGL. AFPM supports this change as it reduces the reporting burden without affecting the accuracy of the emissions associated with the use of the petroleum products and NGLs nor impacts validation of the reported emissions.
Response:  EPA thanks the commenter for their support.
Definitions: NGL and bulk NGL
Commenter Name:  David Friedman, Vice President, Regulatory Affairs,
Commenter Affiliation:  American Fuel & Petrochemical Manufacturers (AFPM)
Document Control Number:  EPA-HQ-OAR-2012-0934-0060-A1
Comment Excerpt Number:  8
Comment:  EPA proposes to include definitions of natural gas liquids (NGL) and bulk NGLs for Subpart MM. The definitions identify the difference between an undifferentiated or bulk NGL stream and an individual differentiated NGL stream, generally ethane, propane, butanes, or pentanes-plus (natural gasoline), that must be reported individually. AFPM supports the inclusion of these definitions, as it removes the ambiguity around NGL reporting.
Response:  EPA thanks the commenter for their support.
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Commenter Name:  Karin Ritter, Manager, Regulatory and Scientific Affairs
Commenter Affiliation:  American Petroleum Institute (API)
Document Control Number:  EPA-HQ-OAR-2012-0934-0047-A2
Comment Excerpt Number:  34
Comment:  EPA is proposing to include the definitions of natural gas liquids (NGL) and bulk NGLs in the subpart MM definitions at 40 CFR 98.397 to clarify the distinction between NGL and bulk NGL for reporting purposes under subpart MM.
"Bulk NGLs for purposes of reporting under this subpart means mixtures of NGLs that are sold or delivered as undifferentiated product."
"Natural gas liquids (NGLs)" for purposes of reporting under subpart MM means hydrocarbons that are separated from natural gas as liquids through the process of absorption, condensation, adsorption, or other methods, and are sold or delivered as differentiated product. Generally, such liquids consist of ethane, propane, butanes, or pentanes plus."
Those subject to subpart MM are required to report NGLs as the individual differentiated product and are not required to conduct testing to determine additional components (i.e., impurities) that are contained within the differentiated product. For a mixture, the individual components should be reported. For example, if a refinery receives a known mixture of propane and ethane, the refiner must report the quantities of propane and ethane individually. Undifferentiated NGLs would be reported as bulk NGLs for subpart MM. We are also proposing to clarify the reporting requirements for bulk NGLs and NGLs. NGLs should be reported either as differentiated NGLs or as bulk NGLs. The requirement at 40 CFR 98.396(a)(22) is proposed to be modified to specify that NGLs reported in 40 CFR 98.396(a)(2) should not be reported again in 40 CFR 98.396(a)(22).
API supports these definitions for Subpart MM purposes.
Response:  EPA thanks the commenter for their support.
Revisions to Table MM-1
Commenter Name:  Karin Ritter, Manager, Regulatory and Scientific Affairs
Commenter Affiliation:  American Petroleum Institute (API)
Document Control Number:  EPA-HQ-OAR-2012-0934-0047-A2
Comment Excerpt Number:  35
Comment:  EPA is proposing to revise the default density and emission factors in Table MM-1 for propane, propylene, ethane, ethylene, isobutane, isobutylene, butane, and butylene. Because these compounds are gases under standard conditions, the default density metric must be presented using a stated temperature and pressure. For all compounds except ethylene, EPA is proposing estimates of density and calculated emission factors at 60 degrees F and saturation pressure, the standard temperature and pressure conditions used by industry. For ethylene, because it cannot be liquefied above 48.6°F, we have selected as a basis for the values of density and emission factor conditions at 41°F (slightly under the critical temperature) and the corresponding saturation pressure. The current and proposed values for default density and emission factors are included in the following.
API supports the proposed revisions as they are more in line with values reported in API's Compendium.
The proposed rule changes and preamble do not discuss whether the changes for the emission factors and density values apply to reports starting in 2013, or if the values are to be retroactively applied to previous reports. API opposes applying these revisions to previously submitted reports. Reporters should not have to resubmit reports to incorporate these changes for calendar year 2010, 2011, or 2012 reporting. These revisions should only apply going forward.
EPA should restrain from frequent revisions to default factors, as any changes made to the factors in the rule requires companies to make changes to their internal reporting systems and processes to align with the revised factors in the rule and subsequent changes to the reporting forms and XML schema. These are not trivial activities. This incurs costs and requires time for the reporting companies to implement and test these changes.
Response:  EPA agrees with the commenter that reporters would not need to resubmit their annual reports on account of the revisions to Table MM-1 that are being finalized in this rule.
Other comments on proposed subpart MM Technical Corrections
Commenter Name:  Karin Ritter, Manager, Regulatory and Scientific Affairs
Commenter Affiliation:  American Petroleum Institute (API)
Document Control Number:  EPA-HQ-OAR-2012-0934-0047-A2
Comment Excerpt Number:  29
Comment:  EPA is proposing the following revision to 98.394(a)(1): "The quantity of petroleum products, natural gas liquids, and biomass, as well as the quantity of crude oil measured on site at a refinery, shall be determined as follows:"
API supports this revision.
Response:  EPA thanks the commenter for their support.
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Commenter Name:  Karin Ritter, Manager, Regulatory and Scientific Affairs
Commenter Affiliation:  American Petroleum Institute (API)
Document Control Number:  EPA-HQ-OAR-2012-0934-0047-A2
Comment Excerpt Number:  30
Comment:  EPA is proposing the following revision to 98.394(a)(3): "The annual quantity of crude oil not measured on site at a refinery received shall be determined according to one of the following methods. You may use an appropriate standard method published by a consensus-based standards organization or you may use an industry standard practice."
API supports this revision.
Response:  EPA thanks the commenter for their support.
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Commenter Name:  Karin Ritter, Manager, Regulatory and Scientific Affairs
Commenter Affiliation:  American Petroleum Institute (API)
Document Control Number:  EPA-HQ-OAR-2012-0934-0047-A2
Comment Excerpt Number:  31
Comment:  EPA is proposing harmonizing changes to 40 CFR 98.394(b) to make the equipment calibration requirements for petroleum products suppliers consistent with other Part 98 calibration requirements. The requirements for equipment calibration in 40 CFR part 98, subpart A (General Provisions) allow for postponement of calibrations for units and processes that operate continuously with infrequent outages. EPA is proposing similar provisions be incorporated into the subpart MM equipment calibration requirements. The proposed changes would also provide flexibility for reporters meeting the equipment calibration requirements.
The added regulatory language is: 98.394(b)(3) "For units and processes that operate continuously with infrequent outages, it may not be possible to complete the calibration of a flow meter or other measurement device without disrupting normal process operation. In such cases, the owner or operator may postpone the calibration until the next scheduled maintenance outage. The best available information from company records may be used in the interim. Such postponements shall be documented in the monitoring plan that is required under §98.3(g)(5)."
API supports the added flexibility associated with this revision.
Response:  EPA thanks the commenter for their support.

Comments on Rule issues not proposed related to reporting and recordkeeping requirements
Commenter Name:  Marla Benyshek, Director, Fuels Regulatory Issues
Commenter Affiliation:  Phillips 66 Research Center
Document Control Number:  EPA-HQ-OAR-2012-0934-0046-A1
Comment Excerpt Number:  3
Comment:  Changes should be made to eliminate reporting of products that will not be combusted. Currently, the regulation requires refineries to calculate emissions that would occur if a product stream is combusted. There are several streams that should be exempted from the calculations because they will not be combusted. An example is lubricating oils. A more specific example is packaged lube oils (e.g. quart bottles) that are exported. Another example is asphalt. This issue was commented on in the original proposed rulemaking by the American Petroleum Institute (API) and others. We urge the EPA to exempt these types of product streams from reporting. This would result in further reporting streamlining and simplification.
Response:  Comprehensive upstream data will provide EPA with a full accounting of the emissions that would result from the complete combustion or oxidation of all petroleum products and natural gas liquids introduced into the economy. Furthermore, comprehensive facility- level data can help us conduct a more robust mass balance assessment for data verification purposes. While we recognize that carbon in some petroleum products, such as asphalt, can remain un-oxidized for long periods, petroleum product suppliers cannot always know with certainty whether or not the carbon in their products will be released into the atmosphere. Even asphalt can be burned as fuel or incinerated as waste. In the Inventory of U.S. Greenhouse Gas Emissions and Sinks, EPA notes several areas of uncertainty surrounding the fate of carbon in petroleum products including those for which the Inventory assumes a 100 percent storage factor for the purposes of the national inventory (e.g., asphalt roofing, asphalt cement, and asphalt paving materials). Therefore, streams will not be exempted from the calculations because they will not be combusted.
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Commenter Name:  Marla Benyshek, Director, Fuels Regulatory Issues
Commenter Affiliation:  Phillips 66 Research Center
Document Control Number:  EPA-HQ-OAR-2012-0934-0046-A1
Comment Excerpt Number:  4
Comment:  We would like to thank EPA for recognizing the need to modify and simplify Subpart MM. The proposed changes will make the reporting requirements less burdensome. However, we would like to see a few additional changes including complete elimination of any crude reporting requirements, elimination of required reporting of measurement methods, and exemption of some product streams from reporting.
Response:  See responses to EPA-HQ-OAR-2012-0934-0046-A1, Excerpts 1, 2, and 3.
Revisions to Subpart NN
Revisions to definition of LDC
Commenter Name:  Pamela Lacey, Senior Managing Counsel, Environment
Commenter Affiliation:  American Gas Association (AGA)
Document Control Number:  EPA-HQ-OAR-2012-0934-0080-A2
Comment Excerpt Number:  1
Comment:  We support the proposal to align the definition of LDC in Subpart NN with the definition in Subpart W to clarify that a gas utility's operations in each state are considered a separate LDC. This change will help reduce confusion in our member's annual reporting process. We also support the revision to clarify that interstate and intrastate pipelines delivering natural gas either directly to large industrial users or farm taps upstream of the inlet to an LDC's distribution system are not included in the definition of an LDC. This clarifying revision makes sense, because these deliveries are not part of an LDC's distribution system. It also helps align Subpart NN with Subpart W.
Response:  EPA thanks the commenter for their support.
Revisions to Equations NN-5 and NN-6
Commenter Name:  Pamela Lacey, Senior Managing Counsel, Environment
Commenter Affiliation:  American Gas Association (AGA)
Document Control Number:  EPA-HQ-OAR-2012-0934-0080-A2
Comment Excerpt Number:  2
Comment:  EPA also proposes to allow flexibility to use different emission factors (rather than just the current single emission factor) for different natural gas streams in Equation NN-5, in response to comments that the multiple streams of natural gas may have different characteristics, such as High Heating Value (HHV). See preamble at page 19827. AGA supports this revision.
Response:  EPA thanks the commenter for their support.
Revisions to reporting requirements for large customer meters
Commenter Name:  Pamela Lacey, Senior Managing Counsel, Environment
Commenter Affiliation:  American Gas Association (AGA)
Document Control Number:  EPA-HQ-OAR-2012-0934-0080-A2
Comment Excerpt Number:  3
Comment:  EPA explains in the preamble that it is proposing to revise 40 C.F.R. 98.406(b)(7) so that instead of requiring LDCs to report annual volume of natural gas delivered to "each meter registering supply equal or greater than 460,000 thousand cubic feet (Mscf) during the calendar year," in future LDCs would be required to report natural gas deliveries "per customer rather than per meter" if the LDC "knows" that a series of meters "serves one particular customer" that receives more that the reporting threshold of 460,000 Mscf. See 78 Fed. Reg. at 19827. In the proposed regulatory text at 98.403(b)(2), EPA uses slightly different language, but with the same ambiguity. The revised text would require LDCs to report the "[t]otal annual volume of natural gas supplied to this end user, if known, otherwise, the annual volume supplied to this meter (Mscf per year)." 78 Fed. Reg. at 19871 (definition of "Fuel" in Equation NN-4; see also preceding definition of CO2 k -  requiring reporting of annual CO2 mass emissions per "end user" rather than per meter).
AGA appreciates EPA's motivation for the change, to significantly minimize double counting emissions that large customers directly report to EPA under Subparts C and D with the emissions estimated for those large customers and reported by fuel suppliers under Subpart NN. We share your goal of developing a more accurate estimate and inventory of greenhouse gas emissions. However, our members are concerned that the proposed revision would be inconsistent with the way that customers are often billed, and the proposal does not make it clear how they could ensure compliance.
First, how deeply into corporate records would an LDC would have to dig in order to back up an assertion that the LDC does not "know" whether a series of meters serves one large customer?
Second, we assume you mean to require reporting where a series of meters serving a customer at one location provide a total throughput exceeding the annual 460,000 Mscf reporting threshold, but this is not clear either in the proposed revised rule section 98.403(b)(2) or in the preamble explanation. On the other hand, your proposed sections 98.404(a)(7) and 98.406(b)(7) are clearer because they refer to the end user's "facility." In 98.406(b)(7), the proposal calls for reporting gas delivered by the LDC to each "end user facility" in excess of the threshold. It would be helpful to use this "end user facility" term consistently in the rule and preamble.
Our two concerns are related. Quite often, large corporations with multiple facilities at different locations across a state will receive one gas utility bill for their multiple facilities and meters, and it is not clear which meter aligns with which facility. Are there a series of meters serving "one customer"? Yes. But are one or more meters located at the same address or facility? It may not be possible to determine the answer based on readily available records, but perhaps one could answer that question with deeper investigations and calling the customers or facilities.
To avoid confusion and potentially burdensome investigations into corporate records, AGA urges EPA to clarify that the reporting obligation applies where the LDC knows based on readily available information that multiple meters serve one end user facility. Our members note that in some cases, more than one meter serving a large end user facility may not be in a "series" but instead will be located side-by-side or parallel to one another. We suggest a clarification that would cover either a series or "group" of meters, or simply strike the word "series."
In addition, we are concerned about the potential burden of reporting fuel usage from facilities with a few large meters but many smaller meters. For example, consider a university that is a large end user primarily due to its natural gas-fired, combustion turbine-based cogeneration system. However, the university may also have hundreds of small meters supplying natural gas to individual buildings within the campus, such as classrooms and residence halls. While the total impact from the collection of small meters would be insignificant compared to the cogeneration system, the data collection process for these meters would be a significant burden for the LDC. To address this concern, AGA urges EPA to proposes that only meters with a fuel usage of 50,000 Mscf or greater be included in the large end user's total natural gas usage.
Response:  For the response to the commenter's concerns regarding the difficulty of identifying large end-user facilities supplied by multiple meters, problems of assigning meters to facilities where companies own more than one facility within the state, addition of a 50,000 Mscf threshold for reporting of individual meters, and the level of research LDCs are required to undertake, please see Section II.U.2 of the preamble to the final rule.
The phrase "series of meters" used in the preamble to the proposed amendments means either a group of meters in sequence, or a group of meters arranged side-by-side or in parallel that provide natural gas to a single large end-user facility.
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Commenter Name:  Eldon Lindt, Director of Auditing, Environmental Policy & Services
Commenter Affiliation:  Xcel Energy, Inc.
Document Control Number:  EPA-HQ-OAR-2012-0934-0074-A1
Comment Excerpt Number:  5
Comment:  Under §98.403(b)(2)(i), EPA proposes to require reporting by customer if the LDC has knowledge that a series of meter serves a customer. Specifically, the regulation reads that LDCs should report the "total annual volume of natural gas supplied to this end-user, if known, otherwise, the annual volume supplied to this meter (Mscf per year)." The term "if known" presents some ambiguity. For example, as a courtesy to our customers, one bill is often sent to a company's main office reflecting gas usage for many facilities. In this case, the usage from one individual facility is not readily known. Xcel Energy requests clarification on the clause "if known".
Response:  For the response to this comment, please see Section II.U.2 in the preamble to the final rule.
Revisions to reporting requirements
Commenter Name:  Karin Ritter, Manager, Regulatory and Scientific Affairs
Commenter Affiliation:  American Petroleum Institute (API)
Document Control Number:  EPA-HQ-OAR-2012-0934-0047-A2
Comment Excerpt Number:  36
Comment:  EPA has learned that o-grade as well as y-grade bulk NGLs are fractionated by facilities subject to subpart NN. Additionally, the EPA has learned that some fractionators strip out only a portion of the bulk NGL stream and supply the remaining bulk NGL downstream to other fractionators, where it is separated into its constituent products. Therefore, the EPA is proposing revisions to 40 CFR 98.406(a)(4) to add new reporting elements that require reporting of the quantity of o-grade, y-grade, and other types of bulk NGLs received, and the quantity not fractionated, but supplied downstream.
API has no issues with these revisions.
Response:  EPA thanks the commenter for their support.
Revisions to Table NN-1 or NN-2
Commenter Name:  Karin Ritter, Manager, Regulatory and Scientific Affairs
Commenter Affiliation:  American Petroleum Institute (API)
Document Control Number:  EPA-HQ-OAR-2012-0934-0047-A2
Comment Excerpt Number:  37