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

    In the 1996 Landfills NSPS Background Information Document,\48\ the
EPA ``decided not to include materials separation requirements within
the final rules because the EPA continues to believe RCRA and local
regulations are the most appropriate vehicle to address wide-ranging
issues associated with solid waste management for landfills.'' The EPA
continues to believe that this is the case. The EPA has, however,
proposed three compliance flexibilities as discussed in sections VI.B
(wellhead monitoring), VII.A (Tier 4 emission threshold determination),
and VIII.B (Criteria for Capping or Removing a GCCS) of this preamble
that may aid landfills in increasing organics diversion. The proposed
adjustments to wellhead operating standards provide some GCCS
operational flexibility to accommodate declining LFG quantity or
quality resulting from modified waste composition at landfills
employing an organic diversion program. The formats of the Tier 4
option and alternative set of surface emission-based GCCS removal
criteria serve as built-in incentives for the landfill owner or
operator to implement a variety of surface emission reduction
techniques, including organics diversion.
---------------------------------------------------------------------------

    \48\ Air Emissions from Municipal Solid Waste Landfills--
Background Information for Proposed Standards and Guidelines, U.S.
EPA (EPA-450/3-90-011a) (NTIS PB 91-197061).
---------------------------------------------------------------------------

    In addition to the three compliance flexibilities discussed in
sections VI.B (wellhead monitoring), VII.A (Tier 4 emission threshold
determination), and VIII.B (criteria for capping or removing a GCCS),
the EPA is seeking comment on other compliance flexibilities it should
consider when issuing the final Emission Guidelines to encourage more
organics diversion. The EPA is also requesting comment on other ways we
could structure the guidelines to credit organics diversion.
    In response to public input, the EPA is also seeking comment on
what, if any, role organics diversion policies or measures could play
in an approvable state plan. The EPA must ensure that each state plan
establishes requirements for LFG emission controls that are at least as
stringent as the Emission Guidelines. We are, therefore, interested in
how states might demonstrate that a state plan that contains organics
diversion policies and measures is at least as stringent as the
Emission Guidelines. The EPA is interested in supporting state organics
diversion initiatives and one way of doing this may be to provide
flexibility to include such initiatives as a component of an approvable
state plan. As previously stated, however, to be approvable, a state
plan must be at least as stringent in its effect on LFG as the Emission
Guidelines, i.e., it must ensure emission reductions equivalent to
those achieved with a well-designed, installed, and well-operated GCCS
with a NMOC destruction efficiency of 98 percent and we request
comments on how a state that relies on organics diversion could do
this. The EPA, through its various voluntary programs intends to
explore the creation of outreach materials, technical assistance
documents, trainings, and other tools or resources for educating owners
and operators of affected landfills and implementing authorities about
the benefits of organics diversion and how organics diversion programs
can be implemented effectively to achieve additional reductions in
methane and NMOC emissions from landfills. The EPA is also exploring
opportunities through its voluntary programs to recognize leadership in
diverting organics from landfills.

B. What data and control costs did the EPA consider in evaluating
potential changes to the timing of installing, expanding, and removing
the GCCS?

    To examine the potential impact of changes to the timing of
initiating and removing landfill gas collection and control, the EPA
updated a dataset of information for landfills, as described below, and
applied a model to assess when controls were needed under the baseline
control scenario (2.5 million

Mg design capacity threshold and 50 Mg/yr NMOC threshold) as well as
various regulatory options.
    As discussed at 79 FR 41805 in determining whether to revise the
proposed standards of performance for new MSW landfills, the EPA
developed a dataset of information for landfills, which included
landfill-specific data such as landfill open and closure year, landfill
design capacity, landfill design area, and landfill depth. For the
regulatory analysis, we approximated the number of landfills that would
become subject to the regulation based on size using the reported
design capacities, which were provided in units of megagrams. For
purposes of rule applicability, size is based on both mass (Mg) and
volume (m\3\).
    The EPA made several significant updates to this original dataset
to evaluate the impacts of this proposal. Notably, the EPA updated the
technical attributes of over 1,200 landfills based on new detailed data
reported to 40 CFR part 98, subpart HH of the Greenhouse Gas Reporting
Program (GHGRP). In addition, the EPA consulted with its regional
offices, as well as state and local authorities, to identify landfills
expected to undergo a modification within the next 5 years. According
to the applicability of the proposed subpart XXX, if a landfill
commenced construction on its modification after July 17, 2014, it
would no longer be subject to the state or federal plans implementing
these proposed revisions to the Emission Guidelines; therefore, these
landfills were excluded from the impacts analysis conducted for this
proposal, and their impacts will be considered as part of the final
revisions to the standards of performance for new (and modified)
landfills issued under 40 CFR part 60, subpart XXX. After incorporating
all of the updates to the inventory and taking out the landfills
expected to modify, the revised dataset now has 1,839 existing
landfills that accepted waste after 1987 \49\ and opened prior to 2014
\50\ that are analyzed in this regulatory options analysis. A detailed
discussion of updates made to the landfill dataset is in the docketed
memorandum, ``Summary of Updated Landfill Dataset Used in the Cost and
Emission Reduction Analysis of Landfills Regulations. 2015.''
---------------------------------------------------------------------------

    \49\ November 8, 1987, is the date on which permit programs were
established under the Hazardous and Solid Waste Amendments of RCRA.
This date was also selected as the regulatory cutoff in the emission
guidelines for landfills no longer receiving wastes because the EPA
judged states would be able to identify active facilities as of this
date. The data available to EPA includes an open year without the
month and so the analysis uses a cutoff year of 1988 for landfill
closure year.
    \50\ July 17, 2014, is the proposed date of the revised NSPS for
MSW landfills in 40 CFR part 60, subpart XXX. A landfill opening or
commencing construction on its modification after this date would
become subject to this new subpart and would not be subject to the
revised emission guidelines. The EPA cannot predict the exact month
a model landfill will open so the analysis uses a cutoff year of
2014.
---------------------------------------------------------------------------

    The EPA programmed a Microsoft[supreg] Access database (hereinafter
referred to as the ``model'') to calculate the costs and emission
reductions associated with the regulatory options for each of the
landfills in the revised dataset. The default parameters for methane
generation potential (L0), the methane generation rate (k),
and the NMOC concentration used to estimate when the landfills exceeded
regulatory emission thresholds and estimate emission reductions are the
same as those discussed at 79 FR 41805. Similarly, the default
parameters for methane generation potential (L0), the
methane generation rate (k), and the NMOC concentration used to
estimate when landfills could cap or remove controls are the same as
those discussed at 79 FR 41805.
    When modeled landfill gas emissions for a particular landfill
exceeded the emission rate threshold, the EPA assumed that collection
equipment was installed and started operating at the landfill 30 months
after first exceeding the threshold (as discussed in the docketed
memorandum ``Methodology for Estimating Cost and Emission Impacts of
MSW Landfills Regulations. 2014''). The EPA also assumed that as the
landfill was filled over time, the landfill would expand the GCCS into
new areas of waste placement according to an expansion lag time of 5
years for active areas and 2 years for areas that are closed or at
final grade. Based on input received during public outreach to small
entity representatives (SERs) as well as comments received on the
proposed NSPS (79 FR 41796), most modern large landfills do not reach
final grade within 2 years and a majority of landfills are complying
with the 5 year provision.
    Although we are proposing a new Tier 4 option as a site-specific
alternative for determining if a landfill has exceeded the regulatory
emission threshold (and must install controls) or if a landfill has
fallen below the regulatory emission threshold (and can remove or cap
controls), the number and types of landfills that could opt to use a
Tier 4 option are unknown and could not be incorporated into the
impacts calculated in the model. As a result, the number of landfills
expected to control under each regulatory option, as well as the
estimated emission reductions and costs associated with each regulatory
option are based on modeled estimates of landfill gas emissions. To
estimate the costs of each regulatory option, the EPA made minor
changes to the cost methodology discussed in the landfills NSPS
proposal at 79 FR 41805. In this analysis, cost equations were obtained
from a recent update to EPA's Landfill Gas Energy Cost Model (LFGcost-
Web), version 3.0, which was updated by EPA's Landfill Methane Outreach
Program (LMOP) in August 2014. The EPA also updated estimates for
surface emission monitoring costs based on revised estimates made
available to the EPA since proposal of the NSPS in July 2014.
    The capital costs continue to be presented in year 2012 dollars and
annualized using an interest rate of 7 percent over the lifetime of the
equipment (typically 15 years), or in the case of drill mobilization
costs, the length of time between each wellfield expansion. These
annualized capital costs were added to the annual operating and
maintenance costs estimated by LFGcost-Web. The annualized cost
includes capital related to the purchase, installation, operation and
maintenance of GCCS, and costs related to testing and monitoring.
    For certain landfills that were expected to generate revenue by
using the LFG for energy, the EPA also estimated LFG energy recovery
rates and associated costs to install and operate the energy recovery
equipment as well as the revenue streams from the recovered energy.
These revenues were subtracted from the annualized capital and
operating and maintenance costs at each landfill in order to obtain a
net cost estimate for each option in each year. The emission reduction
and cost and revenue equations and assumptions are detailed in the
docketed memoranda, ``Updated Methodology for Estimating Cost and
Emission Impacts of MSW Landfills Regulations. 2015'' and ``Updated
Methodology for Estimating Testing and Monitoring Costs for the MSW
Landfill Regulations. 2015.''

C. What emissions and emission reduction programs are associated with
existing MSW landfills?

    The EPA estimates that the potential uncontrolled emissions from
the approximately 1,800 landfills in its regulatory analysis dataset
(as explained in section V.B of this preamble) are approximately 69,700
Mg NMOC and 11.0 million Mg methane (275 million mtCO2e) in
year 2014. In year 2025, the EPA estimates that the potential

uncontrolled emissions from the approximately 1,800 landfills in the
dataset are approximately 71,400 Mg NMOC and 11.2 million Mg methane
(281 million mtCO2e). The majority of landfills in the
dataset are expected to remain open through 2025, thus uncontrolled
emissions are higher in 2025.
    Looking beyond the modeled dataset, the Inventory of U.S.
Greenhouse Gas Emissions and Sinks: 1990-2013 shows a growth in
uncontrolled emissions from MSW landfills, from 205.4 teragrams (Tg)
CO2e in 1990 to 332.6 Tg CO2e in 2013.\51\ If
controls are considered, emissions from landfills have decreased from
173.8 Tg CO2e in 1990 to 97.5 Tg CO2e in 2013
from both regulatory and voluntary programs as discussed below.\52\
---------------------------------------------------------------------------

    \51\ U.S. EPA. Inventory of U.S. Greenhouse Gas Emissions and
Sinks: 1990-2013. April 2015. Table 7-3. http://www.epa.gov/climatechange/ghgemissions/usinventoryreport.html.
    \52\ Ibid, Annex 3.14, Table A-265.
---------------------------------------------------------------------------

1. Emission Reductions Due to Subparts Cc and WWW
    To estimate the emission reductions, the EPA applied the current
design capacity and NMOC emission rate thresholds in the MSW landfills
regulations, and the time allowed for installing, expanding and
removing the GCCS to the modeled emission estimates discussed in
section V.B of this preamble.
    Table 2 of this preamble summarizes the reductions anticipated to
be achieved in 2025 as a result of 40 CFR part 60, subpart WWW and the
federal and state plans implementing the Emission Guidelines. This
table reflects the current baseline level of control at existing
landfills: Landfills greater than or equal to 2.5 million Mg and 2.5
million m\3\ must install a GCCS when NMOC emissions reach or exceed 50
Mg/yr. The table includes emission reductions for NMOC and methane.

                                                               Table 2--Baseline Emission Reductions in 2025 at Existing Landfills
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                   Number of
                                                    Number of      landfills      Annual net   Annual NMOC  Annual  methane    Annual CO2e      NMOC cost       Methane cost        CO2e cost
          Number of  landfills affected             landfills    reporting but       cost      Reductions      reductions      Reductions     effectiveness   effectiveness ($/ effectiveness ($/
                                                   controlling  not controlling    (million      (Mg/yr)    (million Mg/yr)   (million mt/        ($/Mg)             Mg)               mt)
                                                                      \a\         $2012) \b\                                       yr)
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
989.............................................          574              211          299        57,300              9.0             226            5,090              32.3               1.3
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Excludes closed landfills from reporting count, because the closed landfills are not expected to have to submit reports in 2025. They would have already submitted their one-time reports
  under 40 CFR part 60, subpart WWW or the state or federal plan implementing 40 CFR part 60, subpart Cc, and because they are closed, they would also be expected to be done with NMOC
  reporting by 2025 because they are on the tail end of their gas curve and gas rates are declining.
\b\ The annualized net cost ($299 million) is the difference between the average annualized revenue ($1,408 million) and the sum of annualized control cost ($1,700 million) and the average
  annualized testing and monitoring costs ($7.3 million).

    The Emission Guidelines in the baseline are estimated to require
control at 574 of the 989 affected landfills in 2025 and achieve
reductions of 57,300 Mg/yr NMOC and 9.0 million Mg/yr methane (226
million mt/yr CO2e). In the baseline, we estimate that 31
percent (574/1,839) of existing landfills will operate emission
controls in 2025.
2. Other Programs Achieving Emission Reductions From Existing MSW
Landfills
    Landfill owners or operators collect LFG for a variety of reasons:
To control odor, to minimize fire and explosion hazards, to recover LFG
to be used for energy recovery, to sell carbon credits, and to comply
with local, state, or federal air quality standards. This section of
this proposed action discusses several non-EPA programs of which the
EPA is aware. These reductions complement the reductions achieved by
the current NSPS and Emission Guidelines framework.
a. State and Local Ordinances
    The EPA is aware that some state or local ordinances require LFG
combustion. The number of landfills controlling under these ordinances
is unknown and is not factored into the incremental impacts analysis
for this rule. The EPA is also aware that other states have rules
regulating LFG combustion for odor control or safety reasons, which may
be less comprehensive than the requirements of a GCCS operated in
accordance with the NSPS and emission guideline requirements.
b. Market-Based Mechanisms
    Many of these systems may have been installed to recover energy and
generate revenue through the sale of electricity or LFG. Some landfills
with voluntary systems may also receive revenues as a result of the
creation of carbon credits. Data from the Climate Action Reserve
indicates that more than 115 LFG capture projects in 36 states have
been issued credits known as Climate Reserve Tonnes (CRTs).\53\
---------------------------------------------------------------------------

    \53\ Climate Action Reserve. Issued List of CRTs as of January
7, 2015. https://thereserve2.apx.com/myModule/rpt/myrpt.asp?r=112.
---------------------------------------------------------------------------

    To estimate the number of landfills that may be controlling LFG
emissions voluntarily, the EPA evaluated the most current data
available and compared the list of landfills that are modeled to have
installed a GCCS in 2014 in the NSPS/Emission Guidelines dataset to the
list of landfills that are reported to have a GCCS installed in the
LMOP or subpart HH GHGRP databases. While the NSPS/Emission Guidelines
dataset estimates that approximately 620 landfills have installed
controls to meet the requirements of the NSPS or an approved state plan
or federal plan implementing the Emission Guidelines, the LMOP and
GHGRP databases show approximately 330 additional landfills as having
installed controls, resulting in approximately 950 landfills estimated
to have a GCCS installed in 2014.\54\ Approximately 55 percent of these
330 landfills exceed the design capacity of 2.5 million Mg,\55\ but as
of 2014, are not modeled to exceed the NMOC emission threshold that
dictates when a GCCS must be installed. In some cases these GCCS may
have been installed earlier than required by the time frames currently
specified in the NSPS and Emission Guidelines. The LMOP database
estimates that nearly 120 of the 330 landfills with voluntary systems
have an energy recovery component. Among landfills with design
capacities of 2.5 million Mg or greater, approximately 80 of the 180
landfills with a voluntary GCCS have an energy recovery component.
These 330 landfills are estimated to reduce approximately 12 million Mg
CO2e in 2014. This is in addition to the 231 million Mg
CO2e reduction achieved by the current regulatory baseline.
This

represents an additional 5 percent reduction in year 2014 coming from
systems installed for reasons other than compliance with the NSPS or
state and federal plans implementing the Emission Guidelines.
---------------------------------------------------------------------------

    \54\ See sections V.B and V.C of this action for a detailed
discussion of the modeling database and estimated reductions under
the current federal regulatory framework.
    \55\ For the regulatory analysis, we approximated the number of
landfills that would become subject to the regulation based on size
using the reported design capacities, which were provided in units
of megagrams. For purposes of rule applicability size is based on
both mass (Mg) and volume (m\3\).
---------------------------------------------------------------------------

D. What control options did the EPA consider?

    The EPA considered several factors when determining which control
options would represent BSER. This section of the preamble describes
those control options, which include varying the design capacity
threshold, varying the NMOC emission rate threshold, and varying the
time allowed to install and then expand the GCCS. To examine these
options, the EPA ran several permutations of various control options on
the original dataset developed for the July 2014 NSPS proposal. Each
regulatory option assessed variations in the design capacity and/or
emission rate thresholds, as well as changes to the initial lag time
and expansion lag time. The ``initial lag time'' is the time period
between when the landfill exceeds the emission rate threshold and when
controls are required to be installed and started up (30 months in 40
CFR part 60, subparts Cc and WWW). The ``expansion lag time'' is the
amount of time allotted for the landfill to expand the GCCS into new
areas of the landfill (5 years for active areas and 2 years for areas
that are closed or at final grade in 40 CFR part 60, subpart WWW).
    Some options adjusted a single threshold in isolation; for example,
reducing the NMOC emission threshold to between 34 and 40 Mg/yr while
keeping the design capacity threshold constant at 2.5 million Mg. Other
options adjusted multiple control parameters simultaneously, taking
into account the relationship between the parameters. For example,
recognizing that NMOC emissions are a function of waste-in-place, some
options that significantly reduced the NMOC emission threshold also
reduced the design capacity thresholds to 2.0 million Mg to avoid
situations where the NMOC emission threshold would be exceeded long
before the design capacity threshold.
    In addition to adjusting design capacity and emission control
thresholds, other preliminary model runs varied the initial and/or
expansion lag times. These variations estimated the impacts of
requiring landfill owners or operators to install or expand gas
collection systems more quickly after crossing each modeled NMOC
emission threshold.
    In 2013, the EPA presented different model runs during Federalism
consultations and small entity outreach that represented the range of
variation in both the threshold and lag time parameters. For the
options presented, small entity representatives (SERs) and Federalism
consultation participants provided feedback to the EPA, which included
implementation concerns with varying certain parameters as part of the
Emission Guidelines review, as discussed in the following sections. The
EPA also received comments on varying certain parameters in response to
its July 2014 NSPS proposal and ANPRM for Emission Guidelines at MSW
landfills (79 FR 41772) and conducted a subsequent round of Federalism
consultations and small entity outreach in 2015. The EPA considered
these concerns and comments received on the July 2014 NSPS proposal and
ANRPM when developing a revised set of regulatory options in this
proposal.
1. What are the implementation considerations with changing the design
capacity criteria?
    For this proposal, the EPA considered two different design capacity
thresholds: No change from the current regulatory baseline of 2.5
million Mg and 2.5 million m\3\, and an option that reduced the design
capacity to 2.0 million Mg and 2.0 million m\3\. This section of the
preamble describes the resulting potential burden to regulated
entities, including small entities. Potential burden includes obtaining
a title V permit and calculating an annual NMOC emission rate. This
discussion also considers the size threshold associated with existing
state regulations, as well as collection systems that are in place on a
voluntary basis.
    The EPA did not consider an option to remove the design capacity
criteria for this proposal so that all landfills would be affected
sources no matter their size, because of the burdens of permitting and
reporting at small landfills as discussed below and at 79 FR 41782. If
the EPA were to remove the design capacity threshold, a significant
number of additional landfills would be subject to the rule. Out of the
approximately 1,800 existing landfills in the revised dataset,
approximately 850 have a design capacity of less than 2.5 million Mg.
Without a design capacity threshold, the NMOC emission rate would be
the only criterion for installing controls. Thus, these 850 landfills
would be required to begin calculating and reporting their NMOC
emission rate. They would also be required to obtain a Title V permit.
This would present a significant burden on both regulated landfills and
delegated permitting authorities, which must be evaluated in light of
potential emissions reductions.
    The EPA did not analyze control options for landfills with landfill
design capacities less than 2.0 million Mg in the model. Based on the
revised dataset, 571 of the 623 closed landfills (91.6 percent) have a
design capacity less than 2.0 million Mg. Lowering the design capacity
below 2.0 million Mg would cause a large number of closed landfills to
become subject to regulatory requirements including annual NMOC
reporting requirements and Title V permitting requirements.
Additionally depending on NMOC emission rates, a number of these
landfills may also be required to install GCCS despite the fact that
many of these landfills have been closed for many years and are on the
downside of their gas production curve. The EPA concludes lowering the
design capacity threshold below 2.0 million Mg would add regulatory
requirements with minimal environmental benefit. The EPA also notes
that closed landfills may have limited access to additional revenue
because they are no longer collecting tipping fees and the cost for
GCCS and regulatory compliance were not factored into their closure
plans, they may have poor or incomplete records for estimating landfill
gas emissions, and they are less likely to be permitted.
    Several commenters from state agencies expressed concerns with the
permitting and reporting burdens on smaller landfills and advised the
EPA to retain the current design capacity threshold. Another state
agency noted that MSW landfills with a design capacity greater than
0.38 million m\3\ (roughly 15 percent of the current design capacity
threshold in the Emission Guidelines) are required to install GCCSs
under the state's HAP rule. In practice, the smallest landfills
controlling under the state regulation have design capacities as low as
0.6 million Mg and 0.4 million m\3\. The commenter noted that the state
rule has control requirements similar to those in the Emission
Guidelines, but does relax some of the monitoring requirements given
the lower gas quality and smaller emission potential at older and
smaller landfills.
    Two commenters advocated for reducing or eliminating the design
capacity criteria, referencing the state of California Landfill Methane
Rule \56\ (CA LMR), which requires all landfills with

at least 450,000 tons of waste-in-place to assess whether or not GCCS
is required based on other criteria, including estimated heat input
capacity from the landfill gas and surface emissions monitoring data.
---------------------------------------------------------------------------

    \56\ California Code of Regulations, title 17, subchapter 10,
article 4, subarticle 6, sections 95460 to 95476, Methane Emissions
from Municipal Solid Waste.
---------------------------------------------------------------------------

    Based on a review of GCCS data reported in its dataset, the EPA
estimates that over 900 landfills in its revised dataset have installed
a GCCS for either voluntary or regulatory reasons. Of these, 17 percent
of landfills with a capacity less than 2.0 Million Mg report having a
GCCS installed; 47 percent of landfills with a capacity between 2.0
million Mg and 2.5 million Mg have a GCCS installed; and 76 percent of
landfills with a capacity of 2.5 Million Mg or greater have a GCCS
installed.\57\ Thus, it appears that a significant number of landfills
have installed GCCS even in the absence of federal regulation of these
smaller sources, based on site-specific circumstances such as gas
quality and age of waste in the landfill or areas of the landfill,
access to capital, and energy recovery opportunities.
---------------------------------------------------------------------------

    \57\ See Docket Item ``Modeling Database Containing Inputs and
Impacts for Proposed Review of the MSW Emission Guidelines. 2015.''
---------------------------------------------------------------------------

    When the EPA promulgated the 2.5 million Mg and 2.5 million m\3\
design capacity threshold in 1996, we considered the impact on small
entities based on public comment (61 FR 9918, March 12, 1996). Today,
small private entities and municipalities still tend to own smaller
sized landfills, whereas larger private entities tend to own larger
regional landfills. One commenter noted that reducing the design
capacity may disproportionately affect local governments and small
entities. Based on the ownership data reported in the revised dataset,
78 percent of landfills with a design capacity less than 2.0 million Mg
are publicly owned and a similarly strong majority (71 percent) of
landfills between 2.0 million Mg and 2.5 million Mg are publicly owned.
For landfills with a design capacity of 2.5 million Mg or greater, the
share of public ownership drops to 48 percent of landfills. Further,
small entity ownership represents only approximately 8.7 percent of the
landfills required to control under a state or federal plan
implementing subpart Cc. If the EPA were to reduce the design capacity
to 2.0 million Mg and 2.0 million m\3\, approximately 730 landfills
would be subject to control requirements and 70 (9.8 percent) of those
are classified as small entities. If the EPA were to eliminate the
design capacity criteria, approximately 749 additional existing
landfills with a design capacity below 2.0 million Mg (50 percent)
would become subject to the rule, of which 379 are classified as small
entities, with many of these being required to install controls
depending on the NMOC level selected. Further, the cost burden for
installing a collection and control system is more significant for
small landfills, which are more often owned by small entities, compared
to larger landfills. Because certain costs to construct the gas
collection system (e.g., flat fees for drill rig mobilization, and
monitoring and construction costs) remain relatively constant
regardless of the size of the landfill, the per-acre costs to control a
small landfill are more expensive than the per-acre costs to control a
large landfill.
    Assuming an NMOC emission threshold level of 34 Mg/yr, reducing the
design capacity from 2.5 million Mg and 2.5 million m\3\ to 2.0 million
Mg and 2.0 million m\3\ would require controls at an additional 20
landfills that have a design capacity between 2.0 million and 2.5
million Mg, as shown in Table 3 of this preamble. Requiring controls at
landfills in the 2.0 million to 2.5 million Mg size range would be less
cost effective because these landfills have a smaller emission
reduction potential in later years. This is apparent when considering
the percent changes in net control costs and corresponding emission
reductions: net control costs increase by approximately 1.5 percent,
while emission reductions increase by only 0.5 percent in year 2025.
    The EPA does not believe that the additional burden on small
entities and the disproportionate impact on publicly-owned landfills
can be justified in light of the limited additional reduction in
overall emissions and is, therefore, not proposing any changes to the
current design capacity threshold of 2.5 million Mg and 2.5 million
m\3\.
2. What are the implementation considerations with reducing the NMOC
threshold?
    For this proposal, the EPA considered two alternative NMOC emission
thresholds: 40 Mg/yr and 34 Mg/yr. The EPA recognizes that NMOC
emissions are site specific, varying widely from landfill to landfill
and understands that a majority of landfills currently affected by the
federal and state plans implementing the Emission Guidelines conduct
Tier 2 testing in order to refine their NMOC emission estimates before
installing a GCCS. This proposal also allows a new site-specific Tier 4
alternative to determine when a landfill must install a GCCS, as
discussed in sections IV.C and VII.A of this preamble.
    Despite these variations in NMOC emissions, results from the model
show that a lower NMOC emissions threshold could accelerate the
schedule for installing GCCS at existing landfills and also increase
the number of existing landfills required to install controls, thereby
achieving additional reductions of NMOC emissions.
    The EPA proposed on July 17, 2014 a lower NMOC emission threshold
in the NSPS (40 Mg/yr) and discussed this alternative in the ANPRM (79
FR 41772) and several nongovernmental organizations (NGOs) and a local
government entity commented in support of a reduction in the NMOC
emission threshold. One state agency also provided examples of existing
landfills controlling emissions in its state with estimated NMOC
emission rates as low as 8.1 Mg/yr.
    Two commenters expressed concern about whether landfills planning
to install controls based on the current threshold of 50 Mg/yr would be
financially ready to install controls at an earlier time. Other
commenters expressed concern about whether landfills that have closed
and decommissioned their GCCS should be pulled back into control
requirements if their emissions fall between the current 50 Mg/yr
threshold and a more stringent NMOC emission threshold. These
commenters recommended that EPA exempt these landfills from more
stringent control requirements. One of the commenters added that it
would be costly to re-install or refurbish a previously shutdown system
and noted that the system would likely operate for only a few more
years before it once again fell below the more stringent NMOC emission
threshold.
    Other commenters expressed concerns that lowering the NMOC
threshold would jeopardize carbon credit revenues expected from
landfills emitting between 40 and 50 Mg/yr NMOC that were planning on
voluntarily installing a GCCS. A state agency also expressed concern
about the additional burden to delegated authorities of managing a
larger group of landfills. Another state agency expressed concerns that
landfills in arid areas will have difficulty continuously operating a
flare at landfills with lower quality gas that emit between 40 and 50
Mg/yr. Another commenter indicated that older and closed landfills will
struggle to maintain continuous operation of their flare at a lower
NMOC emission threshold and will need to operate the flare with a
supplemental fossil fuel.

    Because of concerns with GCCS operations at landfills that have
closed, the EPA evaluated whether the lower NMOC thresholds of 34 and
40 Mg/yr should apply to this subset of landfills, as discussed in
section VIII.A of this preamble and presented in Table 3 of this
preamble. Because of concerns about areas with low gas quality, the EPA
is proposing changes to address closed or low-gas-quality areas,
including changes to the criteria for capping or removing a GCCS, and
providing for the use of site-specific surface emissions monitoring
measurements to indicate area-specific LFG emissions, as discussed in
section VIII.B of this preamble.
    As shown in Table 3 of this preamble, the incremental cost to
control NMOC at open landfills at a threshold of 34 Mg/yr NMOC is
$17,000/Mg NMOC and $4.3/mtCO2e, compared with $19,300/Mg
NMOC and $4.9/mtCO2e to control at both open and closed
landfills. As discussed in section V.H of this preamble, an NMOC
threshold of 34 Mg/yr at open landfills would achieve reductions of
2,770 Mg/year NMOC and 436,100 Mg/year methane (10.9 million
mtCO2e) compared to the baseline in year 2025. Based on
these considerations, the EPA is proposing to reduce the NMOC emission
threshold from 50 Mg/yr to 34 Mg/yr at open landfills. The EPA is
proposing a separate subcategory for landfills that closed on or before
August 27, 2015, as discussed in section VIII.A of this preamble.
3. What are the implementation concerns with shortening the initial or
expansion lag times?
    In its revised regulatory options analysis for this proposal, the
EPA did not model the impacts from any regulatory options that reduced
the initial or expansion lag times. To a great extent, this decision
was based on our consideration of the numerous implementation and cost
concerns raised by SERs and Federalism consultation participants as
discussed at 79 FR 41807,\58\ as well as in comments received on the
2014 MSW landfills NSPS proposal and ANPRM for Emission Guidelines (79
FR 41772). Those concerns are summarized below. The initial lag time is
the time period between when the landfill exceeds the emission rate
threshold and when controls are required to be installed and started,
and the expansion lag time is the amount of time allotted for the
landfill to expand the GCCS into new areas of the landfill.
---------------------------------------------------------------------------

    \58\ See also the docketed report ``Summary of Small Entity
Outreach. 2014.'' (Docket Item: EPA-HQ-OAR-2003-0215-0051) and the
Final Report of the Small Business Advocacy Review Panel on EPA's
Planned Proposed Rules Standards of Performance for Municipal Solid
Waste Landfills and Emission Guidelines and Compliance Times for
Municipal Solid Waste Landfills, July 2015.
---------------------------------------------------------------------------

    One state agency commented that shortening the current initial lag
time would not allow sufficient time to develop and approve the GCCS
design plan, obtain the necessary permit, and construct the GCCS. The
commenter added that one unintended consequence of shortening the
initial lag time could be the inhibition of the beneficial reuse of
landfill gas, since a shorter lag time may not allow time to design and
approve a more complex landfill gas energy recovery system. Commenters
representing affected landfills also expressed concerns that current
administrative and construction lead times would make shorter lag times
difficult.
    Several landfill owners or operators and a state authority agreed
with costs and operational and safety concerns described at 79 FR 41807
associated with increasing the number of wells in active areas as a
result of shorter initial or expansion lag times. One commenter
provided detailed information on costs to install and repair wells in
active areas, which the commenter estimated to be between two and three
times more expensive than wells installed in areas at final grade. This
commenter added that 43 percent of the wells installed during 2014 were
replacement wells that had to be installed as a result of damage to
existing wells resulting from ongoing activities in active areas and
noted that shortened lag times would only increase the number of
replacement wells required. In addition to the damage to wells from
filling operations, one commenter added that vertical wells in active
areas require additional lateral collection pipes to be installed on
rather flat slopes that are susceptible to condensate blockage and must
also be replaced more frequently. Similarly, two commenters were
concerned whether horizontal collectors could universally meet the need
for shorter lag times in light of the susceptibility of flooding of the
horizontal designs and the inability to dewater these wells with pumps.
    Several commenters recognized the benefit of earlier GCCS
installation, but these commenters also discussed aerobic conditions in
active areas and other factors affecting gas quality that in turn
create exceedances of wellhead monitoring requirements for pressure,
temperature, and oxygen/nitrogen. They noted that few states have
accommodated flexible monitoring alternatives for early collection
systems. One state authority believed that site-specific factors other
than the regulatory-driven lag times, such as safety or odor control,
are already achieving earlier installation of GCCS. Three other
commenters urged EPA to include early collection requirements in the
proposed Emission Guidelines. One of these commenters indicated that
the requirement to promote early collection could be flexible instead
of a rigid adjustment to the lag times. For the reasons presented in
this section as well as those detailed at 79 FR 41807, the EPA is not
proposing to shorten the initial or expansion lag times in the revised
Emission Guidelines. However, the EPA is requesting comment on whether
the regulation should require that the GCCS design plan contain a
description of early gas collection measures or best management
practices, in order for the reviewing professional engineer or the
Administrator to ensure that emissions are minimized. The EPA is also
taking comment on whether the monitoring in the rule should be
strengthened to require GCCS to be expanded in a site-specific manner
as long as surface emission monitoring limits in all areas of the
landfill were maintained at all times, similar to the approach taken in
the California Landfill Methane Rule (LMR).

E. How did we select the proposed options?

    When determining which control options would represent BSER, the
EPA considered several factors: The implementation considerations
identified earlier in this section of this preamble; and the
incremental emission reductions, cost, and co-benefits that would be
achieved beyond the baseline.
    The EPA compared the annualized net cost and emission impacts in
2025 of three different regulatory options to the annualized net costs
and emission impacts in 2025 of the baseline. The EPA analyzed numerous
iterations of alternate control and reporting thresholds and presented
potential control options to SERs and Federalism consultation
participants, as described in section V.D of this preamble. After
considering feedback from the SERs and Federalism consultation
participants, as well as comments received on the July 2014 NSPS
proposal and ANPRM (79 FR 41772), the EPA selected for consideration
three regulatory alternatives as presented in Table 3 of this preamble.
Table 3 summarizes the incremental impacts of each control option, when
compared to the baseline. The table shows the NMOC and methane emission
reductions and

corresponding annualized net costs, when using a 7 percent discount
rate, in 2025.

                                                  Table 3--Emission Reductions and Costs for Control Options in Year 2025 at Existing Landfills
                                                                                [2012$]
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Annual
                                                                Number of                Number of   Annual net    Annual      Annual       CO2e
                                        Landfills affected by   landfills   Number of    landfills      cost        NMOC       methane   reductions    NMOC cost     Methane cost    CO2e cost
                Option                   proposed option \a\    affected    landfills    reporting    (million   reductions  reductions   (million   effectiveness  effectiveness  effectiveness
                                                                   \b\     controlling    but not      $2012)      (Mg/yr)    (million     mt/ yr)       ($/Mg)         ($/Mg)       ($/mt) \c\
                                                                                controlling                            Mg/yr)        \c\
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                Baseline
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Baseline (2.5 million Mg design         All..................         989          574          211         299      57,300         9.0         226          5,100           32.3            1.3
 capacity/50 Mg/yr NMOC).
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                               Incremental values vs. the Baseline
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
Option (2.5 million Mg design capacity/ Open.................           0           62          -62        27.0       1,720        0.27         6.8         15,800            100            4.0
 40 Mg/yr NMOC).                        All..................           0           84          120        48.1       2,500        0.39         9.9         19,200            122            4.9
Option (2.5 million Mg design capacity/ Open.................           0          106         -106        46.8       2,770        0.44        10.9         17,000            108            4.3
 34 Mg/yr NMOC).                        All..................           0          142           62        77.6       4,030        0.64        15.9         19,300            122            4.9
Option (2.0 million Mg design capacity/ Open.................         101          122          -75        51.0       3,040        0.48        12.0         16,800            107            4.3
 34 Mg/yr NMOC).                        All..................         101          162          143        83.5       4,360        0.69        17.2         19,200            122            4.9
------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ Options in this table show the impacts of reducing the design capacity and/or NMOC emission threshold below baseline levels on open landfills only, and retaining the NMOC threshold of 50
  Mg/yr for the closed landfill subcategory as well as reducing the design capacity and/or NMOC emission thresholds for all landfills (open and closed).
\b\ Landfills are affected by the landfills Emission Guidelines based on design capacity. Once affected, they calculate and report emissions until they exceed the NMOC threshold, which
  triggers control requirements.
\c\ Results do not include secondary CO2 impacts.

    Regulatory options. The EPA considered three regulatory options
more stringent than the baseline, as presented in Table 3 of this
preamble. The first option reduces the NMOC emission threshold to 40
Mg/yr. The second option further reduces the NMOC threshold to 34 Mg/
yr. The third option reduces both the NMOC emission threshold to 34 Mg/
yr and the design capacity threshold to 2.0 million Mg and 2.0 million
m\3\. We analyzed the impacts of applying each of these three more
stringent thresholds to only open landfills as well as all (open and
closed) landfills.
    Based on the characteristics of the landfills, between
approximately 60 and 160 additional landfills would be required to
install controls in 2025. In addition to increasing the total number of
landfills that would control their emissions, the schedule for
installing controls would be accelerated for many landfills in years
prior to 2025 because the landfill would exceed the lower thresholds of
34 or 40 Mg/yr NMOC earlier than the baseline, and in turn begin
collecting and destroying landfill gas emissions earlier.
    Emission reductions. If the EPA were to reduce the NMOC emission
threshold to 34 Mg/yr at open landfills while retaining the 2.5 million
Mg and 2.5 million m\3\ design capacity threshold (option 2.5/34) as
proposed in this rule, the corresponding emission reductions in 2025
would be 2,770 Mg/year NMOC and 436,100 Mg/year methane (10.9 million
mtCO2e) compared to the baseline, which represents a 4.8
percent reduction in emissions beyond the baseline. If EPA were to
apply this threshold to all landfills (open and closed), the
corresponding emission reductions in 2025 would be 4,030 Mg/year NMOC
and 635,100 Mg/year methane (15.9 million mtCO2e) compared
to the baseline. Additional reductions could be achieved if the EPA
combined the NMOC emission threshold of 34 Mg/yr with a lower design
capacity threshold of 2.0 million Mg and 2.0 million m\3\ (option 2.0/
34). The corresponding emission reductions for open landfills in 2025
would be 3,040 Mg/yr NMOC and 479,100 Mg/yr methane (12 million
mtCO2e) compared to the baseline for open landfills,
representing a 5.3 percent reduction in emissions beyond the baseline.
If the EPA were to apply this lower threshold for both design capacity
and NMOC to all landfills (open and closed), the corresponding emission
reductions in 2025 would be 4,360 Mg/year NMOC and 687,100 Mg/year
methane (17.2 million mtCO2e) when compared to the baseline.
    If the EPA were to reduce the NMOC threshold to 40 Mg/yr at open
landfills while retaining a 2.5 million Mg and 2.5 million m\3\ design
capacity threshold (option 2.5/40), the emission reductions in 2025
would be 1,720 Mg/year NMOC and 270,700 Mg/year methane (6.8 million
mtCO2e) compared to the baseline. An emission threshold of
40 Mg/yr NMOC with a 2.5 million Mg and 2.5 million m\3\ design
capacity threshold represents approximately a 3 percent reduction in
emissions beyond the baseline. If the EPA were to apply the 40 Mg/yr
NMOC threshold to all landfills (open and closed), the corresponding
emission reductions in 2025 would be 2,500 Mg/year NMOC, 270,000 Mg/
year methane (6.8 million mtCO2e) compared to the baseline.
    The wide range in the magnitude of emission reductions among
pollutants is due to the composition of landfill gas: NMOC represents
less than 1 percent of landfill gas, while methane represents
approximately 50 percent. CO2e is an expression of methane
in terms of the CO2 equivalents, given the methane GWP of
25.\59\
---------------------------------------------------------------------------

    \59\ IPCC Fourth Assessment Report (AR4), 2007. Climate Change
2007: The Physical Science Basis. Contribution of Working Group I to
the Fourth Assessment Report of the Intergovernmental Panel on
Climate Change [Core Writing Team, Pachauri, R.K. and Reisinger, A.
(eds.)]. IPCC, Geneva, Switzerland, 104 pp.
---------------------------------------------------------------------------

    Cost. In terms of control costs in 2025, option 2.5/34 represents
an approximately 16 percent increase in control costs compared to the
baseline if the threshold were reduced for open landfills only, and a
26 percent increase in control costs compared to the baseline if the
threshold were reduced for all landfills (open and closed). If the EPA
adopted a lower NMOC threshold of 34 Mg/yr NMOC along with a reduction
in design capacity to 2.0 million Mg and 2.5 million m\3\, the net cost
would increase by 17 percent above the baseline if applying more
stringent controls only at open landfills, and 28 percent for more
stringent control of all landfills (open and closed). If the EPA
adopted an NMOC threshold of 40 Mg/yr NMOC but retained a design
capacity of 2.5 million Mg and 2.5 million m\3\, the net cost would be
9 percent above the baseline for open landfills and a 16 percent
increase for all landfills.
    In terms of cost effectiveness, the overall dollar-per-Mg cost for
NMOC reductions under the baseline is $5,100 per Mg NMOC and $32.3 per
Mg methane as presented in Table 3 of this

preamble. Under option 2.5/34, the cost effectiveness is $17,000 for
controlling open landfills and $19,300 for all landfills. If the EPA
adopted a lower NMOC threshold of 34 Mg/yr NMOC along with a reduction
in design capacity to 2.0 million Mg and 2.0 million m\3\ (option 2.0/
34), the cost effectiveness is $16,800 for open landfills and $19,200
for all landfills, although the EPA recognizes that this lower cost
effectiveness does not incorporate costs related to additional
permitting needs for sources between 2.0 and 2.5 million Mg and m\3\.
Under option 2.5/40, the incremental dollar-per-Mg control cost for
NMOC reductions is approximately $15,800 per Mg NMOC for open landfills
and $19,200 for all landfills. The EPA welcomes additional data and
comment on the issue of costs.
    Proposed Option 2.5/34. Based on the emission reduction and cost
discussions above and consistent with the President's Methane Strategy
and the potential to achieve a near-term beneficial impact in
mitigating global climate change as discussed in section III of this
preamble, the EPA is proposing to reduce the NMOC threshold to 34 Mg/yr
at open landfills but retain the current design capacity threshold of
2.5 million Mg and 2.5 million m\3\. Lowering the NMOC threshold would
result in earlier GCCS installations at landfills already subject to
the rule based on their design capacity, thereby achieving additional
reductions of NMOC and methane. This lowered threshold achieves
reductions without adjusting the initial and expansion lag times and
incurring the associated costs and implementation concerns.
    Reducing the NMOC threshold from the baseline-level of 50 Mg/yr to
34 Mg/yr at open landfills would affect 106 more landfills in 2025 and
would achieve an estimated 4.8 percent additional reduction in
emissions of NMOC and methane compared to the baseline. These
additional reductions can be achieved at very similar cost
effectiveness to an NMOC threshold of 40 Mg/yr, but a level of 34 Mg/yr
would achieve almost 60 percent more reductions than a level of 40 Mg/
yr. In addition, the proposal is expected to result in the net
reduction of 238,000 Mg CO2, due to reduced demand for
electricity from the grid as landfills generate electricity from
landfill gas. Reducing the NMOC threshold to 34 Mg/yr results in an
incremental reduction of methane that is equivalent to approximately
10.9 million mtCO2e per year, which compares to 19 to 33
million mtCO2e reductions from the April 16, 2012
regulations for the oil and gas industry (77 FR 49490). In addition, as
discussed in section XI.G of this preamble, a level of 34 Mg/yr NMOC
also results in climate-related benefits associated with methane
reductions. The 2025 methane benefits vary by discount rate and range
from about $310 million to approximately $1.7 billion; the mean SC-
CH4 at the 3-percent discount rate results in an estimate of
about $660 million in 2025.
    Further, this proposal would tighten the control device removal
criteria, requiring that the controls would have to stay on until three
successive tests for NMOC emissions were below the NMOC emission
threshold of 34 Mg/yr instead of 50 Mg/yr, unless the landfill can
demonstrate that its surface emissions are low, as discussed in section
VIII.B of this preamble. Depending on the waste-in-place of the
landfill at closure and other site-specific factors (e.g., waste
composition, climate), it may take 15 to 45 years after closure for a
large modern landfill to emit less than the NMOC emission threshold,
and in turn qualify for capping or removing the GCCS. Although the
emission reductions associated with these later years in the landfills'
lifetimes are not incorporated in the environmental and economic
impacts of the baseline and options under consideration in year 2025,
the lower threshold associated with this proposal would require
controls to be installed for a longer period than the baseline.
    Reducing the NMOC threshold also recognizes the opportunity to
build upon progress to date and achieve even more reductions of
landfill gas and its components, consistent with the President's
Methane Strategy as discussed in section III of this preamble. Landfill
gas generated from established waste (waste that has been in place for
at least a year) is typically composed of roughly 50 percent methane
and 50 percent CO2 by volume, with less than 1 percent NMOC.
Because the components of landfill gas are associated with substantial
health, welfare, and climate effects, additional reductions of landfill
gas would improve air quality and reduce health and welfare effects
associated with exposure to landfill gas emissions. Note that in 2013,
landfills continued to be the third largest source of human-related
methane emissions in the U.S., representing 15.3 percent of total
methane emissions.\60\ Methane emissions represent 9.5 percent of all
GHG emissions (in CO2e) in the U.S.\61\
---------------------------------------------------------------------------

    \60\ U.S. EPA. 2013. ``Inventory of U.S. Greenhouse Gas
Emissions and Sinks: 1990-2013. Executive Summary, ES-8.'' Available
at http://www.epa.gov/climatechange/ghgemissions/usinventoryreport.html.
    \61\ Ibid.
---------------------------------------------------------------------------

    The EPA is not proposing to reduce the design capacity in
conjunction with a reduction in the NMOC emission threshold. As
discussed in section VI.E of this preamble, this option achieves only
modest additional reductions (less than one percent more than the
proposed option 2.5/34), but has a disproportionate impact on small
entity- and municipally-owned sites, and closed landfills that are on
the downward trend of generating landfill gas. Reducing the design
capacity would also pose substantial burden on delegated authorities
because these small entity- and municipally- owned landfills are not
affected by the currently promulgated NSPS or Emission Guidelines.
    Alternative Option 2.5/40. The EPA recognizes that the ownership,
operating status, and other technical characteristics of individual
landfills can affect the site-specific cost effectiveness of achieving
additional reductions of NMOC and methane and ability to sustain the
operation of GCCS that may not be readily apparent when selecting a
control option based on the national aggregate values shown in Table 3
of this preamble. The EPA is soliciting comment on whether an NMOC
threshold higher than 34 Mg/yr may be appropriate for all, or a subset
of the existing landfills affected by this proposal, in addition to
retaining the current threshold of 50 Mg/yr for the closed landfill
subcategory, as proposed and discussed in section VIII.A of this
preamble.

VI. Rationale for the Proposed Changes to Monitoring, Recordkeeping,
and Reporting

A. Surface Emissions Monitoring Requirements

    The intent of the surface monitoring provision in the existing
Emission Guidelines is to maintain a tight cover that minimizes the
migration of emissions through the landfill surface. Quarterly surface
emissions monitoring indicates whether the cover and gas collection
system are working properly. In addition to the proposed surface
emission provisions discussed here, the EPA is also seeking comment on
additional enhancements to surface emissions monitoring in section X.B
of this preamble.
    Every Cover Penetration. The EPA proposes that all surface
penetrations must be monitored for existing landfills.

Proposed 40 CFR part 60, subpart Cf specifies that the landfill must
``operate the collection system so that the methane concentration is
less than 500 parts per million above background at the surface of the
landfill. To determine if this level is exceeded, the owner or operator
must conduct surface monitoring around the perimeter of the collection
area along a pattern that traverses the landfill at 30 meter intervals
and where visual observations indicate elevated concentrations of
landfill gas, such as distressed vegetation and cracks or seeps in the
cover and all cover penetrations.''
    Commenters both supported and opposed monitoring every cover
penetration. Several commenters, including two state/local agencies and
one environmental organization supported monitoring every cover
penetration. The state agency noted that seals around penetrations can
be compromised as a result of settlement, separation from the barrier
layers or boot materials, and cracking of cover soils tied into
penetrations, thus, leading to detections of landfill gas during
surface monitoring as reported by field staff. Several commenters
opposed the requirement to monitor every cover penetration, citing
significant additional cost with no or limited environmental benefit.
In proposed 40 CFR part 60, subpart Cf, we are reiterating the position
in the current regulation that landfills must monitor all cover
penetrations and openings within the area of the landfill where waste
has been placed and a gas collection system is required. Specifically,
landfill owners or operators must conduct surface monitoring at 30-
meter intervals and where visual observations indicate elevated
concentrations of landfill gas. The EPA maintains that cover
penetrations can be observed visually and are clearly a place where gas
would be escaping from the cover, so monitoring of them is required by
the regulatory language. The regulatory language gives distressed
vegetation and cracks as an example of a visual indication that gas may
be escaping, but this example does not limit the places that should be
monitored by landfill staff or by enforcement agency inspectors. Thus,
consistent with the EPA's historical intent and interpretation, the
landfill owner or operator must monitor any openings that are within an
area of the landfill where waste has been placed and a gas collection
system is required.
    More Precise Location Data. The EPA is proposing more specific
requirements for reporting the locations where measured methane surface
emissions are 500 parts per million above background. Since the
Emission Guidelines were originally promulgated in 1996, EPA is aware
of new, relatively inexpensive monitoring technologies that incorporate
GPS technologies to more precisely identify the location of
exceedances. The EPA is aware of several landfills that have been using
GPS to more accurately track the location of measurements and store
these data in databases. The EPA is proposing to require landfills to
report the latitude and longitude coordinates of each exceedance using
an instrument with an accuracy of at least 3 meters. Coordinates must
be in decimal degrees with at least five decimal places. This level of
accuracy and precision is consistent with the requirements proposed in
Petroleum Refinery Sector Risk and Technology Review and New Source
Performance Standards (79 FR 36880). This precision will also provide
more transparency to inspectors reviewing site records on the location
of surface emission leaks, and confirming areas of the landfill where
surface monitoring activities were skipped, which may assist with
targeting inspections to problem areas of the landfill. In addition,
this precision will allow the landfill to overlay the coordinates of
surface exceedances against maps of the GCCS to determine spatial and
temporal patterns of exceedances relative to GCCS components. This
specificity for location data is also being required for landfills
using the Tier 4 site-specific measurement approach, as discussed in
section VII.A of this preamble.

B. Wellhead Monitoring Requirements

    The operational standards of the current Emission Guidelines are to
operate each interior wellhead in the collection system with a negative
pressure (vacuum), a landfill gas temperature less than 55 [deg]C and
with either a nitrogen level less than 20 percent or an oxygen level
less than 5 percent. Since 1996, when the rules were originally
promulgated, the EPA has heard concerns from both regulated entities
and implementing authorities regarding the implementation of the
operational standards for temperature and oxygen/nitrogen at wellheads.
The EPA received feedback during 2013 and 2014 from SERs and Federalism
consultation participants expressing concern that the wellhead
standards were overly prescriptive. In the July 17, 2014 proposed NSPS
(79 FR 41821) and the ANPRM for the Emission Guidelines (79 FR 41788),
the EPA discussed whether these parameters should be adjusted in order
to provide monitoring flexibility for landfills while also ensuring
that the GCCS were well operated. The EPA also requested comment on
what types of landfills may be eligible for adjustments to these
wellhead standards; for example, the EPA asked whether only small
entities, or landfills with energy recovery projects should benefit
from this flexible monitoring.
    In response to the July 2014 proposed NSPS (79 FR 41796) and ANPRM
(79 FR 41772), many commenters questioned the need for the current
wellhead operating standards for monitoring pressure, temperature, and
oxygen or nitrogen to assess whether the GCCS was operating
effectively.
    Fire. Industry commenters recognized that the wellhead operational
standards were intended to ensure the landfill gas collection system is
operating properly and to avoid propagation of a subsurface fire or
inhibit anaerobic decomposition, but they asserted that the standards
achieve neither of the latter objectives.
    Commenters asserted that the wellhead monitoring parameters are
poor indicators of landfill fires or inhibited decomposition and impede
proper operation of the collection system without providing any of the
expected benefits. They also explained that landfill operators
typically respond to high temperature and oxygen/nitrogen readings by
reducing flow from the well or expanding the gas collection system.
They explained that both approaches can have unintended and harmful
consequences, including exacerbating a fire, and reducing the
collection efficiency of the GCCS. In addition, they asserted that
expanding a GCCS in an area with poor gas quality or quantity does not
assist with achieving additional reductions. Commenters emphasized the
difficulty of meeting the wellhead standards in areas of the landfill
with declining gas flowrates or gas quality, which is more common in
older or closed areas of the landfill. Several commenters stated that
landfill owners already have inherent incentives to minimize fire risks
in order to protect significant investments in GCCS and energy recovery
infrastructure.
    Flooding. Commenters both agreed and disagreed that surface
emission monitoring and monthly monitoring of pressure at the wellhead
are sufficient to determine if the well is inoperable or functioning
below expected capacity as a result of flooding. Commenters suggested
that landfill gas flowrate measurement is an established technology to
assess well performance and can be measured without removing

the wellhead (unlike measurement of liquid levels) and added that flow
rate measurement is required for landfills affected by the Wisconsin
landfills regulations. The EPA recognizes that this parameter can be
measured using the same equipment used to monitor other wellhead
parameters and it is taking comment on whether to monitor this
parameter in section X of this preamble.
    Wellhead Monitoring and BMPs. In response to the July 17, 2014
ANPRM (79 FR 41772) and NSPS proposal, the EPA received input
indicating that the currently required wellhead operating parameters
(particularly oxygen/nitrogen and temperature), are barriers to, rather
than a part of, a ``well operated'' GCCS and prevent proactive LFG
collection practices such as connecting the GCCS to the leachate
collection system and installing horizontal or other early gas
collectors. Specifically, the EPA received information explaining that
leachate systems are not designed to be air tight and are not
constructed in refuse. The information also indicated that when
leachate collection systems contain liquids, the piping that conveys
the leachate may be unable to collect enough gas until the liquid is
removed and that as a result, when a vacuum is applied, ambient air can
be pulled in as well, leading to elevated oxygen concentrations.
Accordingly, an alternative operating procedure would be needed to
accommodate these higher oxygen levels. The information received
indicates that regulatory agencies have been reluctant to grant these
alternatives.
    It was also pointed out that gas quality and quantity can vary
widely from different systems and at different times within the same
system, which is why horizontal collectors and leachate system
components are not designed to meet the 40 CR part 60, subpart Cc and
WWW operating parameters for pressure, temperature, and nitrogen/oxygen
concentration. Information from a state agency indicated that some
intake of ambient air is likely with leachate collectors and suggested
that operators should have flexibility to decide the balance between
gas flow and oxygen intake and on whether to cease extracting landfill
gas or use another method. The information provided further indicated
that the time delay associated with modifying a GCCS design plan or
getting approval for higher operating values (HOVs) is problematic when
applied to collector pipes used for seep and odor control, since
operators must make these changes more quickly for safety reasons.
    The EPA also received input explaining the benefits of early gas
collection, such as fewer emissions and reduced odors.
    Corrective Action Concerns. Under the current rules, if a landfill
exceeds a wellhead operating parameter, the landfill owner or operator
must initiate corrective action within 5 days and follow the timeline
in 40 CFR part 60, subparts WWW and Cc for correcting the exceedance.
If the exceedance cannot be corrected within the specified timeframe,
the landfill owner or operator should prepare to expand the GCCS. As
commenters note above, exceedances involving elevated temperature and
oxygen/nitrogen concentration are often not solved by expanding the
GCCS, especially in older areas. Several industry commenters, as well
as a state regulatory agency, noted that wellhead corrective action
often requires very site-specific and technical solutions other than
expanding a GCCS and it is not reasonable to develop these actions and
have them approved within the narrow timeframes allowed in the current
rules. A trade association noted that most landfills have occasional
exceedances of wellhead standards and that requests for HOVs are among
the top five paperwork items submitted for landfill GCCS operations.
Given the numerous landfills subject to control requirements as well as
the fact that many landfills could have more than 100 wells installed,
the trade association also noted that the prescriptive review and
approval processes for HOV of wellhead operating standards present a
significant burden for both the landfill and the delegated authority
without an environmental benefit.
    Commenters representing industry, state government, the SBA Office
of Advocacy, and a trade organization called on the EPA to remove
temperature and oxygen/nitrogen wellhead operating parameters from
Emission Guidelines for all landfills. These commenters were all in
agreement that negative pressure and surface monitoring can assure
proper GCCS operation. One commenter noted that landfills with energy
recovery projects will continue to monitor wellhead parameters to
ensure proper equipment operation and maximize revenue from energy
sales, without requiring the monitoring and reporting of these
parameters under the Emission Guidelines. Another commenter noted that
the regulations should provide some flexibility to accommodate
declining gas generation that facilities will experience as a result of
local diversion initiatives.
    Two state agencies requested that the wellhead operating parameters
of temperature and oxygen/nitrogen merely serve as guidance to provide
flexibility, particularly to small entities. One of the commenters
provided an example of monitoring requirements in its state regulation,
which exempts supplemental and/or temporary odor and gas control system
components (e.g., leachate cleanouts, leachate recirculation, early
collectors) from pressure, temperature, and oxygen/nitrogen limits. In
this case, the state does not impose limits for these parameters, but
it does require the landfill to monitor those parameters.
    Two commenters requested that temperature and oxygen/nitrogen
monitoring requirements be continued while maintaining current surface
methane monitoring methods. A state agency noted that wellhead
monitoring can identify subsurface biological and chemical reactions
that can present a safety hazard and cannot be detected by surface
emission monitoring only. An environmental organization explained that
wellhead monitoring provides indicators of conditions that could lead
to subsurface fires, release massive volumes of HAP, and cause terrible
odors and was concerned that removing these requirements prevents the
landfill and the implementing authorities from identifying early
indicators of potential problems. The commenter explained that landfill
owners may have difficulty meeting the requirements due to improper
site management and failure to maintain tight seals, leading to too
much air intake. One city also advocated for more stringent monitoring
in order to more proactively identify odors or other operational
concerns with a GCCS.
    Based on public comments, input from small entities, and our own
analysis of available information, the EPA is proposing to remove the
requirement to meet operational standards for temperature and nitrogen/
oxygen at wellheads and is thus also proposing to remove the
corresponding requirement for corrective action for exceedances of
these parameters. To ensure a well-designed and well-operated GCCS that
minimizes surface emissions, the EPA is proposing to use a combination
of GCCS design and approval requirements as discussed in section VI.C
of this preamble, landfill surface emission monitoring requirements as
discussed in section VI.A of this preamble, and continued maintenance
of negative pressure at wellheads. Based on the feedback provided by
commenters and our analysis of available information, the

EPA believes these adjustments provide more flexibility to landfills,
can result in additional reductions of LFG emissions from other GCCS
components, and will reduce the burden of corrective action on both the
landfill owner or operator and the implementing authority. Based on
public input, the EPA expects that eliminating the operational
standards for oxygen/nitrogen and temperature will drastically reduce
the number of requests for HOVs and alternative timelines for making
corrections while ensuring that the GCCS continues to operate properly.
The procedures for approving HOVs for wellheads not demonstrating
compliance with the negative pressure standard are discussed in section
VI.D of this preamble.
    While the EPA is proposing to remove the requirement to meet
operational standards for temperature and nitrogen/oxygen, the EPA is
proposing that landfill owners or operators continue monthly monitoring
and recordkeeping of the wellhead temperature and oxygen/nitrogen
values, consistent with operational guidance documents and best
practices for operating a GCCS in a safe and efficient
manner.62 63 Based on our evaluation of commenters' concern
that the oxygen/nitrogen and temperature operational standards can be a
limiting factor in promoting earlier and more robust collection of LFG,
the EPA is proposing to no longer require the landfill to take
corrective action if the monitoring of these parameters demonstrates
that a particular value or values is/are exceeded. The EPA is proposing
that landfill owners or operators continue monitoring these parameters
because, as several industry commenters and regulatory agencies stated,
the measurement of these parameters can still serve as useful guidance
for landfill operators and landfill gas energy project operators
because they assess GCCS performance and thus help to periodically
adjust or ``tune'' the GCCS to minimize LFG emissions and maintain safe
operating conditions at the landfill. The equipment used to monitor
wellheads commonly includes these parameters, so these parameters can
be measured at the same time the technician monitors wellhead pressure
without imposing additional burden. The results of this monthly
wellhead monitoring will now be kept as records on site because the EPA
continues to believe these data will be useful for implementing
authorities when approving modifications to the original GCCS design
plan, or when conducting inspections of the site.
---------------------------------------------------------------------------

    \62\ http://www.epa.ohio.gov/portals/27/engineer/eguides/guide78.pdf.
    \63\ http://www.nrel.gov/docs/legosti/fy97/23070.pdf.
---------------------------------------------------------------------------

    The requirement to maintain negative pressure at each wellhead
ensures that gas is being routed to a GCCS that was designed and built
in accordance with a GCCS design plan that has been approved by a
professional engineer. The EPA believes these wellhead standards,
together with the surface emission monitoring requirements, are
effective and limit the possibility of surface emissions of LFG. This
approach also allows landfills and state regulators the time and
flexibility to determine the appropriate response for adjusting
wellfield operations, as needed, without imposing overly prescriptive
requirements. This approach also provides increased flexibility for
landfills to install supplemental and temporary gas collection
components to achieve additional reductions of LFG without the risk of
exceeding oxygen/nitrogen or temperature operational standards.

C. Requirements for Updating the Design Plan

    The EPA is proposing criteria for when an affected source must
update its design plan and submit it to the implementing authority for
approval. We are proposing that a revised design plan must be submitted
as follows: (1) Within 90 days of expanding operations to an area not
covered by the previously approved design plan, and (2) prior to
installing or expanding the gas collection system in a manner other
than as described in a previously approved design plan.
    The EPA is proposing site-specific design plan review and approval
procedures that recognize the unique site-specific topography, climate,
and other factors affecting the design of the GCCS. However, the EPA
solicits comment on ways to streamline the design plan submission and
approval procedures as part of its review of the Emission Guidelines.
Examples of streamlining may include the potential development of a
process by which approved alternative operating parameters could be
automatically linked to updates of design plans or development of a
process by which alternative operating parameters and updated design
plans could be approved on a similar schedule.

D. Submitting Corrective Action Timeline Requests

    We have included provisions in proposed 40 CFR part 60, subpart Cf
(40 CFR 60.36f(a)(3)) to clarify our intent that agency approval of
corrective action timelines is required only if a landfill does not fix
an exceedance in 15 days and is unable to or does not plan to expand
the gas collection system within 120 days. The EPA is clarifying that
``expansion'' of the GCCS means a permanent change that increases the
capacity of the GCCS, such as increasing the size of header pipes,
increasing the blower sizes and capacity, and increasing the number of
wells. Excluding system expansion, all other types of corrective
actions expected to exceed 15 calendar days should be submitted to the
agency for approval of an alternate timeline. In addition, if a
landfill owner or operator expects the system expansion to exceed the
120-day allowance period, it should submit a request and justification
for an alternative timeline. We have not proposed a specific schedule
for submitting these requests for alternative corrective action
timelines because investigating and determining the appropriate
corrective action, as well as the schedule for implementing the
corrective action, will be site specific and depend on the reason for
the exceedance. We clarify that a landfill should submit an alternative
timeline request as soon as possible (i.e., as soon as the owner or
operator knows that it would not be able to correct the exceedance in
15 days or expand the system in 120 days) to avoid being in violation
of the rule. If the landfill were to wait until 120 days after the
exceedance to submit an alternative timeline, then by the time the
regulatory agency has the chance to review the timeline and determine
if it is approvable, the landfill will already be in violation of the
requirement to expand the system within 120 days. After submitting the
alternative timeline request, the landfill should work with its
permitting authority to communicate the reasons for the exceedances,
status of the investigation, and schedule for corrective action.
    To address implementation concerns associated with the time allowed
for corrective action, the EPA requests comment on an alternative that
extends the requirement for notification from 15 days to as soon as
practicable, but no later than 60 days from when an exceedance is
identified. Many requests for an alternative compliance timeline
express the need for additional time to make necessary repairs to a
well that requires significant construction activities. Extending the
time period to as soon as practicable, but no later than 60 days, may
reduce the burden associated with the approval of an alternative
timeline and ensure

sufficient time for correction without significant environmental
detriment. If the EPA were to extend the time period to as soon as
practicable, but no later than 60 days, then the EPA is also
considering the removal of the provision to submit an alternative
timeline for correcting the exceedance. Thus, by no later than day 60,
the landfill would have to either have completed the adjustments and
repairs necessary to correct the exceedance, or be prepared to have the
system expansion completed by day 120. The EPA is also requesting input
on whether 60 days is the appropriate amount of time to allow owners or
operators to make the necessary repairs.

E. Electronic Reporting

    In this proposal, the EPA is describing a process to increase the
ease and efficiency of performance test data submittal while improving
data accessibility. Specifically, the EPA is proposing that owners or
operators of MSW landfills submit electronic copies of required
performance test and performance evaluation reports by direct computer-
to-computer electronic transfer using the EPA-provided software. The
direct computer-to-computer electronic transfer is accomplished through
the EPA's Central Data Exchange (CDX) using the Compliance and
Emissions Data Reporting Interface (CEDRI). The CDX is the EPA's portal
for submittal of electronic data. The EPA-provided software is called
the Electronic Reporting Tool (ERT), which is used to generate
electronic reports of performance tests and evaluations. The ERT
generates an electronic report package that will be submitted using the
CEDRI. The submitted report package will be stored in the CDX archive
(the official copy of record) and the EPA's public database called
WebFIRE. All stakeholders will have access to all reports and data in
WebFIRE and accessing these reports and data will be very
straightforward and easy (see the WebFIRE Report Search and Retrieval
link at http://cfpub.epa.gov/webfire/index.cfm?action=fire.searchERTSubmission). A description and
instructions for use of the ERT can be found at http://www.epa.gov/ttn/chief/ert/index.html, and CEDRI can be accessed through the CDX Web
site at www.epa.gov/cdx. A description of the WebFIRE database is
available at http://cfpub.epa.gov/oarweb/index.cfm?action=fire.main.
    The proposal to submit performance test data electronically to the
EPA applies only to those performance tests conducted using test
methods that are supported by the ERT. The ERT supports most of the
commonly used EPA reference methods. A listing of the pollutants and
test methods supported by the ERT is available at http://www.epa.gov/ttn/chief/ert/index.html.
    We believe that industry would benefit from this proposed approach
to electronic data submittal. Specifically, by using this approach,
industry will save time in the performance test submittal process.
Additionally, the standardized format that the ERT uses allows sources
to create a more complete test report resulting in less time spent on
data backfilling if a source failed to include all data elements
required to be submitted. Also through this proposal, industry may only
need to submit a report once to meet the requirements of the applicable
subpart because stakeholders can readily access these reports from the
WebFIRE database. This also benefits industry by cutting back on
recordkeeping costs as the performance test reports that are submitted
to the EPA using CEDRI are no longer required to be retained in hard
copy, thereby, reducing staff time needed to coordinate these records.
    Since the EPA will already have performance test data in hand,
another benefit to industry is that fewer or less substantial data
collection requests in conjunction with prospective required residual
risk assessments or technology reviews will be needed. This would
result in a decrease in staff time needed to respond to data collection
requests.
    State, local, and tribal air pollution control agencies will also
benefit from having electronic versions of the reports they are now
receiving because they will be able to conduct a more streamlined and
accurate review of electronic data submitted to them. For example, the
ERT would allow for an electronic review process, rather than a manual
data assessment, making review and evaluation of the source provided
data and calculations easier and more efficient. In addition, the
public will also benefit from electronic reporting of emissions data
because the electronic data will be easier for the public to access.
How the air emissions data are collected, accessed, and reviewed will
be more transparent for all stakeholders.
    One major advantage of the proposed submittal of performance test
data through the ERT is a standardized method to compile and store much
of the documentation required to be reported by this rule. The ERT
clearly states what testing information would be required by the test
method and has the ability to house additional data elements that might
be required by a delegated authority.
    In addition, the EPA must have performance test data to conduct
effective reviews of CAA section 111 standards, as well as for many
other purposes, including compliance determinations, emission factor
development, and annual emission rate determinations. In conducting
these required reviews, the EPA has found it ineffective and time
consuming, not only for us, but also for regulatory agencies and source
owners or operators, to locate, collect, and submit performance test
data. In recent years, stack testing firms have typically collected
performance test data in electronic format, making it possible to move
to an electronic data submittal system that would increase the ease and
efficiency of data submittal and improve data accessibility.
    A common complaint from industry and regulators is that emission
factors are outdated or not representative of a particular source
category. With timely receipt and incorporation of data from most
performance tests, the EPA would be able to ensure that emission
factors, when updated, represent the most current range of operational
practices. Finally, another benefit of the proposed data submittal to
WebFIRE electronically is that these data would greatly improve the
overall quality of existing and new emissions factors by supplementing
the pool of emissions test data for establishing emissions factors
    In summary, in addition to supporting regulation development,
control strategy development, and other air pollution control
activities, having an electronic database populated with performance
test data would save industry, state/local/tribal agencies, and the EPA
significant time, money, and effort while also improving the quality of
emission inventories, air quality regulations, and enhancing the
public's access to this important information.

VII. Rationale for Proposed Alternative Emission Threshold
Determination Techniques

    The EPA is proposing an emission threshold determination based on
site-specific surface emissions monitoring (SEM) that provides
flexibility for when a landfill must install and operate a GCCS. If the
owner or operator limits landfill surface methane emissions and can
demonstrate that those emissions are below 500 ppm methane for 4
consecutive quarters, then the requirement to install a GCCS is not
triggered even though estimates using Tiers 1, 2, and/or 3 may show
that the landfill's annual NMOC emissions have exceeded the regulatory
threshold. In

addition, the Tier 4 surface emission approach could also be used as
one of the criteria for determining when a GCCS can be removed or
partially removed or decommissioned at closed landfills or closed areas
of active landfills, as discussed in sections IV.D and VIII.C of this
preamble.
    The idea to measure site-specific surface emissions to help
determine the timing of GCCS installation was presented while the EPA
was conducting outreach with small entities during its review of the
landfills regulations in 2014. Small entities recommended a new Tier 4
surface emission demonstration to allow increased flexibility for
landfills that exceed modeled NMOC emission rates to demonstrate that
site-specific methane emissions are actually low prior to being
required to install a GCCS. In addition, the Environmental Defense Fund
(EDF) presented the idea of a surface concentration threshold as one of
many potential alternatives to increase emission reductions from
landfills in its January 2013 whitepaper.\64\ The EPA presented and
solicited comments on potential Tier 4 procedures in both the NSPS
proposal for new landfills and the ANPRM for existing landfills (79 FR
41772).
---------------------------------------------------------------------------

    \64\ Environmental Defense Fund. Recommendations and
Considerations for EPA's Forthcoming Revisions to Section 111
Standards for MSW Landfills. January 2, 2013. See EPA-HQ-OAR-2003-
0215-0050.
---------------------------------------------------------------------------

    Many commenters, representing both industry and environmental
interests, supported the Tier 4 SEM approach for determining when a
GCCS must be installed. These commenters stated that the option to
conduct site-specific measurements using SEM is a more accurate
indication of when gas collection is necessary to reduce emissions,
compared to modeled emission rates. However, one commenter on the NSPS
proposed rule opposed the inclusion of a Tier 4 option for new
landfills, stating that it allows a subset of new landfills to delay
methane capture requirements when these landfills will be required to
install a GCCS in the future and should have a GCCS designed and
installed during landfill construction. Other commenters expressed
concern about state agencies lack of experience and time to determine
whether Tier 4 monitoring requires a GCCS to be installed and requested
guidance for Tier 4 implementation procedures.
    Many commenters identified the potential benefits of a Tier 4
option. Commenters representing both industry and environmental
interests noted that the SEM option will encourage landfill owners and
operators to implement methane reduction practices, such as the use of
oxidative landfill covers, organic waste diversion, and interim gas
control measures (horizontal gas collectors, connecting a leachate
collection recovery system into a GCCS), noting that such practices can
be implemented more quickly and more cost-effectively than a GCCS
installed in accordance with the design plan requirements of the
current Emission Guidelines. Commenters indicated that a SEM method
reflects actual site-specific emissions data that account for gas
generation differentials attributed to climate variations, waste
acceptance rates, and cover soil materials that vary between landfills
in different regions of the U.S. One commenter indicated that the use
of SEM in determining the need to install a GCCS would reduce costs and
energy consumption for landfills otherwise required to install
controls, that would not generate a sufficient amount of gas to support
a collection system but would remain below surface emission thresholds
based on site-specific measurements. Another commenter added that a
Tier 4 approach grants additional flexibility and a potential cost
savings compared to the Tier 2 method, but cautioned that a surface
monitoring methodology needs to be developed that is functional during
windy conditions.
    Commenters also considered how to implement a Tier 4 approach,
including the hierarchy of the new tier relative to the existing tiers,
procedures for conducting the SEM, the level of the appropriate
exceedance, and what to do upon an exceedance. Several commenters
suggested that Tier 4 could be employed at any point following a Tier 1
or Tier 2 test where the calculated NMOC emission rate is greater than
the NMOC threshold for installing a GCCS. These same commenters
suggested that landfill owners and operators have the option to perform
Tier 4 SEM testing in the same areas and using the same methods
currently established in 40 CFR part 60, subpart WWW. These commenters
recommended that if an exceedance occurs during Tier 4 SEM testing,
then landfill owners or operators should follow the same procedures and
timelines for remediation and re-monitoring as outlined in subpart WWW.
These commenters further suggested that if an exceedance cannot be
remediated under the existing subpart WWW procedures, then the landfill
would be required to prepare a GCCS design plan within 1 year of the
initial exceedance and install a GCCS within the monitored area within
30 months of the initial exceedance. These commenters further suggested
that if during the initial monitoring event methane surface emissions
do not exceed 500 ppm over background, then the installation of a GCCS
is not required and routine SEM should be performed until the landfill
or area of the landfill is closed. One commenter requested that the EPA
propose a surface concentration level of 200 ppm and indicated that
this level provides empirical confirmation that the landfill is ready
to install a GCCS.
    After considering public comments and input from small entity
outreach, the EPA is proposing Tier 4 SEM procedures for determining
when a landfill must install a GCCS. Tier 4 allows landfill owners or
operators to demonstrate that site-specific surface methane emissions
are low. Under Tier 4, as proposed in this proposed rule, if the site-
specific surface methane emissions are below 500 ppm for 4 consecutive
quarters, then the requirement to install and operate a GCCS has not
been triggered even in circumstances where emission estimates using
Tiers 1, 2, and/or 3 are above the regulatory threshold. However, any
quarterly surface emissions value over 500 ppm would trigger the
requirement to install and begin operating a GCCS. If the landfill opts
to use Tier 4 for its emission threshold determination and there is any
measured concentration of methane of 500 parts per million or greater
from the surface of the landfill, the owner or operator must install a
GCCS, and it cannot go back to using Tiers 1, 2 or 3. The landfill
owner or operator would be required to submit a design plan within 1
year of reporting the surface emissions value over 500 ppm to the
implementing authority in an annual report and would be required to
install and start up a GCCS within 30 months of reporting the surface
emissions value over 500 ppm.
    The SEM demonstration would be conducted using the SEM procedures
described in sections IV.B and VI.A of this preamble. SEM would be
conducted around the perimeter of the landfill and the required
traverse every 30 meters for the entire landfill. Note that the EPA is
requesting comment on enhanced surface monitoring, including the 30
meter traverse pattern, in section X.B of this preamble. The Tier 4
provisions can be utilized by any landfill that has exceeded the design
capacity threshold. The Tier 4 provisions provide an incentive for a
landfill owner or operator to keep surface emissions low as described
later in this section.
    Under this proposal, if a landfill exceeds the modeled NMOC
emission

rate under Tier 1, then the landfill may choose to estimate the NMOC
emission rate by using the Tier 2 or 3 procedures or measure actual
surface emissions using Tier 4. If a landfill failed a Tier 4 test, the
landfill would trigger the requirement to submit a design plan and to
install and operate a GCCS. However, if a landfill failed a Tier 2 or 3
test, proposed 40 CFR part 60, subpart Cf allows the landfill to test
using a ``higher'' tier, including Tier 4. For example, if a landfill
exceeds the proposed NMOC emission rate of 34 Mg/yr using Tier 2, then
the landfill may choose to calculate the NMOC emission rate using Tier
3, or the landfill may choose to demonstrate that site-specific surface
methane emissions are below 500 ppm using Tier 4. Tier 1 is the most
conservative method for estimating NMOC emissions and models NMOC
emissions based on default values for methane generation rate (k),
methane generation potential (Lo), and NMOC concentration
(CNMOC). Tier 1 takes the least effort and expense to
conduct, but tends to overestimate NMOC emissions given the
conservative default parameters. A landfill would likely use Tier 1 for
its initial estimate of NMOC emissions. Tier 2 models NMOC emissions
based on the same default values for methane generation rate and
methane generation potential, which are in turn based on waste
composition and climate data, but allows the landfill owner or operator
to determine a site-specific NMOC concentration. Under Tier 2,
landfills would incur a more substantial cost to determine the site-
specific NMOC concentration. Tier 3 also models NMOC emissions, but
adds another site-specific measurement for a methane generation rate
using Method 2E. Under Tier 3, landfills would incur a substantial cost
to determine the site-specific methane generation rate. Industry
experience and public comments indicate that sites do not frequently
use Tier 3 because of the expense. Commenters stated that the Tier 3
test is extremely rare because of the high cost and the fact that in
many geographical areas the ``k'' factor (methane generation rate
constant) is not reduced via testing. There are a significant number of
landfills reporting under the Tier 2 method, which allows the site to
measure a site-specific NMOC concentration instead of using the higher
default NMOC concentrations required under the Tier 1 calculations,
however, Tier 3 is not widely used. Thus, we are proposing to allow
landfills to conduct Tier 4 testing after a failed Tier 1, Tier 2, or
Tier 3 test.
    A landfill owner or operator may undertake Tier 4 SEM testing upon
submitting an annual NMOC emission rate report that shows an NMOC
emission rate greater than 34 Mg/yr using Tier 1, 2, or 3 procedures.
If the landfill owner or operator chooses to undertake Tier 4 SEM
instead of submitting a design plan and installing and operating a GCCS
or estimating the NMOC emission rate using the next higher tier, then
the landfill owner or operator would begin keeping records of all Tier
4 SEM readings and submit a ``Tier 4 SEM report'' as its next annual
report. The report would include and identify the number of SEM
readings above 500 ppm. If the report shows any SEM readings above 500
ppm methane, then the landfill would be required to submit a GCCS
design plan within one year and install and begin operating a GCCS
within 30 months. (The landfill could not take corrective action to
correct the Tier 4 exceedance and could not estimate the annual NMOC
emission rate using Tiers 1, 2, or 3.)
    If the Tier 4 SEM report shows no SEM readings above 500 ppm for 4
consecutive quarters, then the landfill may continue Tier 4 monitoring
at a reduced semi-annual frequency or return to Tier 1, 2, or 3. This
approach allows owners or operators some flexibility to select the tier
that is most applicable to their landfill, based on the point each
landfill is in its lifecycle, and other site-specific factors. Note
that a landfill can recalculate NMOC using Tiers 1, 2, or 3 only if it
has 4 consecutive quarters with no SEM readings above 500 ppm.
    The EPA selected a 500 ppm threshold for Tier 4 because it is
consistent with the level the EPA determined to be appropriate to
demonstrate that a GCCS is well-designed and well operated. In other
words, when conducted properly, SEM is a good indicator of how well a
GCCS is operating overall. For landfills without a GCCS (including
those that may be using other LFG mitigation strategies), the level of
500 will demonstrate that site-specific surface methane emissions are
as low as those allowed at a landfill with a well-operated and well-
designed GCCS in place. See the docketed memorandum ``Establishing a
Site-Specific Emission Threshold Alternative for MSW Landfills, 2015.''
Therefore the EPA believes this alternative site-specific concentration
threshold will achieve the goal of minimizing methane emissions to the
atmosphere. The EPA is aware that the surface emission threshold for
installing a GCCS under the CA LMR is 200 ppm. However, the EPA also
notes that CA LMR retains the 500 ppm level as an appropriate level for
instantaneous SEM readings for areas already controlled by a GCCS.
California ARB initially proposed a 200 ppm SEM threshold for both GCCS
installation and for GCCS operation in its regulation, but finalized
500 ppm for GCCS operation because a lower threshold could cause an
operator to overdraw the vacuum on the GCCS (to avoid a surface
exceedance), which in turn could draw in too much oxygen and possibly
cause fires. The EPA recognizes the concerns with setting the threshold
too low, which may cause operators of voluntary GCCS to overdraw the
vacuum on the GCCS, and has proposed a level of 500 ppm. The EPA
requests comment on whether a level between 200 and 500 ppm is
appropriate for the Tier 4 provisions, and whether setting the level
below a specific point in this range poses fire or other safety
concerns for operating a GCCS. The EPA also requests data that might
support a different surface emissions threshold.
    The EPA requests comments on whether landfill owners or operators
should provide notification to EPA when conducting Tier 4 surface
emissions monitoring. Such notification would be similar to the
performance test notification required by 40 CFR 60.8(d), wherein the
owner or operator of an affected facility provides the Administrator at
least 30 days prior notice of any performance test to afford the
Administrator the opportunity to have an observer present.
    As noted earlier in this section, commenters representing both
industry and environmental interests noted that the Tier 4 SEM option
would encourage landfill owners or operators to implement alternative
methane reduction practices, such as the use of oxidative landfill
covers, interim gas control measures, and organic waste diversion. The
EPA agrees. Such measures can directly affect surface emissions and
when employed would help a landfill ensure that surface emissions are
low, enabling a landfill to delay the regulatory requirement to install
a GCCS without a significant negative impact on public health or the
environment. Section V.A of this preamble discusses alternative methane
reduction practices, such as the use of oxidative landfill covers,
interim gas control measures, and organic waste diversion.

VIII. Proposed Changes To Address Closed or Non-Producing Areas

    The EPA recognizes that many landfills or landfill areas are closed
or

have inactive areas that do not produce as much LFG. The production of
LFG naturally declines over time as an area stops accepting waste and
the amount of degradable organic content declines. In the ANPRM for the
Emission Guidelines (79 FR 41772), the EPA requested input on ways to
ensure emissions are minimized in the later stages of a landfill's
lifecycle (79 FR 41783). Specifically, the EPA sought input on whether
the current criteria for capping or removing a GCCS are appropriate:
(1) The landfill is closed, (2) the GCCS has been in operation for 15
years, and (3) three successive tests for NMOC emissions are below the
NMOC emission threshold. We also sought input on alternative approaches
to determining when it is appropriate to cap or remove a GCCS, such as
consecutive quarterly measurements that would demonstrate that surface
emissions are low.

A. Subcategory for Closed Landfills

    The EPA notes that many existing landfills in our dataset closed at
various points since 1987, including landfills that closed as many as
18 years prior to this proposed action. In the ANPRM, the EPA presented
the distribution of existing landfills by closure date (see Table 3, 79
FR 41792). These data showed that nearly 80 percent of the existing
landfills with a design capacity of at least 2.5 million Mg and 2.5
million m\3\ were active landfills as of 2014. Similarly, 77 percent of
the cumulative waste disposed in these existing landfills were at
active landfills. The EPA recognizes that these active landfills are
the most significant sources of LFG emissions at existing landfills.
    The EPA evaluated the costs and benefits of controlling emissions
at a level between 34 Mg/yr and 40 Mg/yr at both open and closed
landfills. Table 3 of section V.E of this preamble presents the number
of landfills affected and the corresponding emission reductions and
costs. The EPA also considered how closed landfills would be affected
by this proposal. We are considering ``closed'' landfills to be those
that closed after 1987 but on or before the date of this proposal.
    At the baseline NMOC emission threshold of 50 Mg/yr, the EPA
estimates that 29 of the 233 closed landfills with a design capacity of
at least 2.5 million Mg and 2.5 million m\3\ would be required to
install controls. At an NMOC emission threshold of 40 Mg/yr, the EPA
estimates that an additional 22 landfills beyond the baseline would be
required to install controls, resulting in controls at approximately 51
\65\ closed landfills in 2025. The LFG controlled at these 51 closed
landfills represents approximately 6 percent of the total emission
reductions achieved from all active and closed landfills expected to
control emissions at a level of 40 Mg/yr NMOC in year 2025. At the
proposed NMOC emission threshold of 34 Mg/yr, the EPA estimates that an
additional 36 landfills beyond the baseline would be required to
install controls, resulting in controls at approximately 65 \66\ closed
landfills in 2025. The LFG controlled at these 65 closed landfills
represents less than 7 percent of the total emission reductions
achieved from all active and closed landfills expected to control
emissions at a level of 34 Mg/yr NMOC in year 2025.
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    \65\ 22 closed landfills plus 29 closed landfills.
    \66\ 36 closed landfills plus 29 closed landfills.
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    An NMOC emission rate threshold of 34 Mg/yr NMOC at closed
landfills would achieve an additional 1,260 Mg NMOC and 5 million
mtCO2e as compared to retaining the threshold of 50 Mg/yr
NMOC for these closed sites. These reductions would be achieved at an
incremental control cost effectiveness of $23,700 per Mg NMOC and $6
per mtCO2e for closed landfills in 2025 (excluding
additional testing and monitoring costs).
    See the docketed memorandum ``Revised Cost and Emission Impacts
Resulting from the Landfill EG Review (2015)'' for additional detail on
the impacts on closed landfills. In addition to these control costs,
the EPA estimates that 160 closed landfills that are not controlling in
2025 would be required to estimate and report NMOC emissions under the
proposed option because they have a design capacity of at least 2.5
million Mg and 2.5 million m\3\.
    After closure, the gas flows at landfills decline and the ability
to achieve additional reductions also declines. The EPA received input
from SERs that many closed landfills supplement their flare with pilot
(fossil) fuels in order to maintain flare operation despite declining
gas quantities and quality. These SERs were concerned that a lower
threshold at these closed landfills would extend the amount of pilot
fuel necessary for flame stability. The EPA notes that closed landfills
may have limited access to additional revenue because they are no
longer collecting tipping fees and the cost for GCCS and regulatory
compliance were not factored into their closure plans. Further, many
SERs expressed concerns that many compliance costs are fixed cost
items, regardless of the operating status of the landfill, such as
permitting fees, drill rig mobilization fees, and others, as discussed
in section V.D.1 of this preamble. Many SERs also expressed concerns
about staffing limitations at closed landfills, who may have limited
staff to oversee extended GCCS design, operations, maintenance, and
compliance. For landfills that closed after August 27, 2015, the EPA
understands that gas quality will remain a concern and it has provided
an alternative set of GCCS removal criteria based on site-specific
emissions, as discussed in section VIII.B of this preamble.
    Commenters expressed concern about whether landfills that have
closed and decommissioned their GCCS should be pulled back into control
requirements if their emissions fall between the current 50 Mg/yr
threshold and a more stringent NMOC emission threshold. These
commenters recommended that the EPA exempt these landfills from more
stringent control requirements. One commenter added that it would be
costly to re-install or refurbish a previously shutdown system and
noted that the system would likely operate for only a few more years
before the landfill fell below the more stringent NMOC emission
threshold. For example, the proposed reduction of the NMOC emission
rate threshold to 34 Mg/yr NMOC could affect landfills that installed a
GCCS to comply with the 50 Mg/yr NMOC emissions threshold in 40 CFR
part 60, subpart WWW (or the state plans or federal plan implementing
40 CFR part 60, subpart Cc), but whose emissions are still above the
EPA's proposed 34 Mg/yr NMOC threshold. These landfills could have
declining gas flows, could be closed, or could have met the 40 CFR part
60, subpart WWW criteria for capping or removing the GCCS.
    To address concerns about closed landfills, the EPA is proposing to
create a subcategory of closed landfills, to which an NMOC emission
rate threshold of 50 Mg/yr would apply, instead of an NMOC emission
rate of 34 Mg/yr. The subcategory of closed landfills is proposed to be
defined as a landfill that has submitted a closure report as specified
in 40 CFR 60.38f(f) on or before August 27, 2015. As noted above, the
emissions associated with the 65 closed landfills represents less than
7 percent of the total emission reductions achieved from all active and
closed landfills expected to control emissions at a level of 34 Mg/yr
NMOC in year 2025. The EPA believes this proposed subcategory for
closed landfills alleviates concerns with lowering the threshold for
closed

landfills, while focusing the proposed changes to the regulatory
framework on emission reductions from the existing landfills
contributing most significantly to methane emissions from MSW
landfills.
    The EPA is requesting input on whether the proposed subcategory for
closed landfills is the most appropriate method for controlling
emissions and addressing concerns with closed landfills, or whether the
EPA should consider exempting closed landfills from the proposed
subpart Cf entirely. The EPA is also requesting comments on whether
additional provisions should be considered for closed landfills when
establishing the revised Emission Guidelines, including whether the
closed landfill subcategory should be expanded to include landfills
that closed within 13 months after publication of the Emission
Guidelines in the Federal Register.

B. Criteria for Capping or Removing a GCCS

    Several commenters requested that the EPA reconsider the 15-year
criteria for capping or removing a GCCS and one commenter stated that
the 15-year period should be longer, rather than shorter. Commenters
supported the use of Tier 4 SEM procedures to help determine the
removal or decommissioning of existing GCCS. Commenters supported the
use of SEM to allow the flexibility to confirm when a closed landfill
or closed area of a landfill no longer producing gas in significant
quantities can remove or decommission all or a portion of the GCCS.
Several of these commenters referenced a rationale similar to the one
they provided for supporting the use of Tier 4 SEM for determining GCCS
installation as discussed in section VII.A of this preamble. Several
commenters requested that the EPA provide a ``step-down'' procedure for
scaling down GCCS operations in non-producing areas and allowing a GCCS
to be removed from rule applicability.
    The EPA is proposing two sets of criteria for capping and removing
the GCCS. The first set of criteria is similar to the criteria in
subpart Cc, but has been adjusted to reflect the new NMOC emission
threshold proposed in this proposal: (1) The landfill is closed, (2)
the GCCS has been in operation for 15 years, and (3) three successive
tests for NMOC emissions are below the proposed NMOC emission threshold
of 34 Mg/yr for open landfills and 50 Mg/yr NMOC for closed landfills.
The EPA is also proposing an alternative set of criteria for capping or
removing the GCCS that employs a SEM demonstration: (1) The landfill,
or an area of an active landfill, is closed, (2) the GCCS has operated
for at least 15 years or the landfill owner or operator can demonstrate
that the GCCS will be unable to operate for 15 years due to declining
gas flows, and (3) the owner or operator demonstrates for 4 consecutive
quarters that there are no surface emissions of 500 ppm or greater from
the landfill or closed area. The EPA selected a level of 500 ppm to be
consistent with the operational standard for operating a GCCS. The
operational standard is the surface emissions level that cannot be
exceeded once a GCCS has been installed.
    The EPA proposes the use of SEM procedures in section VI.A of this
preamble for determining when to decommission wells and for when the
landfill can cap or remove a GCCS. If a landfill owner or operator can
demonstrate that surface emissions in the closed area of an open
landfill or a closed landfill are below 500 ppm for 4 consecutive
quarters, then they would be able to stop collecting gas from that area
or the landfill as a whole. After 4 consecutive quarters of no
exceedances, the landfill continues to monitor the closed area annually
for surface emission exceedances of 500 ppm or greater. If exceedances
are found, the landfill must restart the GCCS in the closed area and
the GCCS would be required to operate according to proposed 40 CFR part
60, subpart Cf.
    As discussed in section VII.A of this preamble, surface emissions
monitoring more closely reflects the site's actual emissions and
accounts for differences in gas generation due to waste composition and
local conditions. As discussed in section VII.A of this preamble, sites
will have the incentive to employ various technologies or practices to
minimize surface emissions, thus giving the owner or operator
flexibility at both the installation and removal stages of LFG
collection and control. With these rule provisions, the EPA can ensure
environmental protection is demonstrated through low surface emissions
and landfill owners or operators will have the flexibility to cap or
remove the GCCS based on site-specific surface emission readings.

C. Non-Producing Areas and Wellhead Standards

    Commenters have identified the difficulty of operating a GCCS in
``non-producing'' areas and meeting the wellhead operational standards
for the GCCS. They have also contended that the corrective action--
expanding the GCCS, is counter to a ``well-operated'' GCCS. Several
commenters requested that the EPA provide flexibility to meet the
wellhead and other requirements in ``non-producing'' areas. Commenters
generally consider a ``non-producing'' area as one with declining LFG
generation and gas flow, which in turn make it difficult to
continuously meet the operational standards for a GCCS. One commenter
stated that when landfill gas production decreases significantly, even
small amounts of vacuum can draw air into the waste mass causing
exceedances of the wellhead oxygen parameter. The commenter added that
the landfill owner or operator may address the oxygen exceedance by
reducing the vacuum to a very low level, but then may not be able to
maintain negative pressure. Another commenter stated that LFG wells in
old waste can be very sensitive to vacuum adjustments, easily exceeding
the 5 percent oxygen standard not due to excessive air infiltration,
but rather due to low LFG volume. Other commenters noted that the
difficulty of meeting the wellhead oxygen/nitrogen operational
standards could be exacerbated if the EPA were to reduce the NMOC
emissions threshold below 50 Mg/yr.
    As discussed in section VI.B of this preamble, the EPA proposes to
remove the requirement to meet wellhead operating standards for
temperature and nitrogen/oxygen. Removing these two standards will not
only promote earlier and more robust collection of LFG as discussed in
section VI.B of this preamble, but will also give owners or operators
flexibility to operate the GCCS in non-producing or closed areas
without the risk of exceeding the oxygen/nitrogen operating standards.
Removing the requirement to meet the oxygen/nitrogen operating
standards and the need for corrective action, including expanding the
GCCS, will reduce the burden on both the landfill owner or operator and
the implementing authority. As discussed in section VIII.B of this
preamble, the EPA is also providing flexibility for temporary
decommissioning of wells in closed landfills or closed areas of active
landfills to provide flexibility for meeting negative pressure in areas
that can demonstrate low surface emissions.

IX. Rationale for the Other Proposed Changes

A. Landfill Gas Treatment

    The EPA is proposing a definition of treated landfill gas and
treatment system. A Treatment system would be defined as a system that
filters, de-waters, and compresses landfill gas to levels determined by
the landfill owner

or operator based on the beneficial end use of the gas. The EPA is
proposing this definition to provide compliance flexibility and to
promote the beneficial use of LFG. The approach works in conjunction
with the EPA's proposed expansion of the use of treated landfill gas
beyond use as a fuel for a stationary combustion device to include
other beneficial uses such as vehicle fuel, production of high-Btu gas
for pipeline injection, and use as a raw material in a chemical
manufacturing process. This definition would be available for all MSW
landfill owners or operators.
    The approach is consistent with public comments received on
previous landfills documents (67 FR 36475, May 23, 2002; 71 FR 53271,
September 8, 2006; 79 FR 41796, July 17, 2014; 79 FR 41772, July 17,
2014), as well as input from participants in small entity outreach, who
stated that the extent of filtration, de-watering, and compression can
be site- and equipment-dependent, and that different sites require
different levels of gas treatment to protect the combustion devices
that use treated LFG as a fuel and ensure good combustion.
    Commenters on the proposed NSPS (79 FR 41796) and ANPRM (79 FR
41772) supported the expanded use of treated LFG. Commenters including
state/local agencies, a large landfill owner or operator, and an
industry trade association supported the expanded beneficial use of LFG
to include uses beyond subsequent sale or use and agreed that a broader
definition is appropriate. No commenters opposed the expanded use.
    Many commenters on the July 17, 2014 proposed NSPS (79 FR 41796)
and ANPRM (79 FR 41772) opposed a definition of LFG treatment based on
specific numerical values for filtration and de-watering. Numerous
commenters disagreed with a requirement to meet specific absolute
filtration and dew point suppression values and contended that a ``one-
size-fits-all'' approach was not appropriate, and would not reduce
emissions. One commenter specifically noted the impact that the costs
of these requirements would have on small entities.
    Commenters estimated costs to comply with the dew point reduction.
Based on experience, commenters estimated that chillers alone would
cost $500,000 each. Commenters estimated that instrumentation,
monitoring, and controls would cost an additional $150,000 per chiller,
plus up to $60,000 for annual maintenance, monitoring, and operation.
These commenters also expressed concerns about the timeframe for
installing chillers. Plus, many commenters also expressed concern that
the numerical requirements would be detrimental to existing and
potential beneficial use projects, including potentially shutting down
existing beneficial use projects and preventing future ones.
    On the other hand, many commenters supported the more flexible
definition of treatment system that allows the level of treatment to be
tailored to the type and design of the specific project equipment.
Commenters pointed out that owners and operators of combustion
equipment are already motivated to treat landfill gas to manufacturer
specifications to protect equipment and maintain warranties. Commenters
added that compliance with a site-specific definition of treatment can
be tracked using a preventative maintenance plan.
    The EPA recognizes that the landfill industry continues to develop
new LFG beneficial use projects and the EPA continues to support the
recovery and use of LFG as an energy source. Thus, the EPA is proposing
a simplified definition of treatment as filtering, de-watering, and
compressing landfill gas, but is retaining as alternative a definition
of LFG treatment based on specific numerical values for filtration and
de-watering.
    The simplified definition of treatment, combined with site- and
equipment-specific monitoring, is expected to provide compliance
flexibility, ensure environmental protection, and promote the
beneficial use of LFG. The proposed definition would allow the level of
filtration, dewatering, and compression to be tailored to the type and
design of the specific equipment in which the LFG is used. Owners or
operators would need to identify monitoring parameters, be able to
demonstrate that such parameters effectively monitor filtration, de-
watering or compression system performance necessary for the end use of
the treated LFG and keep records to demonstrate that the parameters are
being met.
    Owners or operators would also need to develop a site-specific
treatment system monitoring plan that would not only accommodate site-
specific and end-use specific treatment requirements for different
energy recovery technologies, but would also ensure environmental
protection. A well-operated system with a level of treatment specific
to the site and end-use equipment would prevent equipment disruptions
and limit emissions resulting during shutdowns or malfunctions. A
treatment approach that can be tailored to the end use of the gas would
also promote wider use of LFG energy recovery, by limiting the
compliance burden for those landfills opting to include an energy