processed together, it is unlikely that the contaminants would be at a
level of concern. Rejected bales and boxes are sent to a landfill and
are not used as fuel. Additional testing requirements are in place to
assure that packaging is of suitable purity for mills producing
recycled paper that will be used for food-contact packaging.
---------------------------------------------------------------------------

    \97\ Standard specifications for buying and selling of materials
issued by the Institute of Scrap Recycling Industries Inc.
---------------------------------------------------------------------------

    Response: The Agency disagrees that the presence of foreign
materials in OCC rejects undergoing recycling should not be of concern.
Combustion of such materials remaining in the PRRs after recycling
constitute burning of a solid waste; and as such, units burning those
materials would be subject to CAA section 129 standards. Information
received from commenters states that the inspection practices described
above prevent the introduction of other discarded materials and are
standard practice. Based on that information, and examination of the
few cases in the boiler database of foreign materials present in OCC
rejects undergoing recycling,\98\ the Agency has concluded that such
situations are incidental, and no specific conditions to ensure the
containers are empty are warranted, other than to describe the
incidental contamination as part of the categorical listing. The Agency
reiterates, however, that the combustion of discarded materials in PRRs
would result in the application of the CAA section 129 standards.
---------------------------------------------------------------------------

    \98\ December 2011 boiler database--Boiler Reconsideration
Proposal Databases: Emissions Database for Boilers and Process
Heaters Containing Stack Test, CEM, & Fuel Analysis Data Reported
under ICR No. 2286.01 & ICR No. 2286.03 (version 7); http://epa.gov/ttn/atw/boiler/boilerpg.html.
---------------------------------------------------------------------------

iii. Combustion Off-Site
    Comment: Under D.C. Circuit precedent, the use of PRRs by the paper
industry should not be treated any differently from the use of the PRRs
by the generator. AMC I, at 1186, 1192-93 (materials recycled in an
ongoing industrial process are not discarded and materials that are
destined for beneficial use by the generating industry itself are not
waste because such materials are not part of the waste disposal
problem). Mills that do not combust solid fuel can and do send PRRs to
mills that have that capability.
    Response: For combustion at PRRs within the paper recycling
industry, the Agency examined the data in the record from previous
rulemakings as well as comments received on the proposal. The Agency
has determined that it is appropriate to revise the proposed to include
PRRs generated by paper recycling mills that are transferred off-site
to other paper recycling mills for energy recovery. This determination
addresses those generators that do not have the capability to combust
the materials on-site, but who wish to transfer their PRRs off-site for
combustion at the estimated 15-20 paper recycling mills that do have
the solid fuel boilers capable of burning PRRs for energy recovery. The
PRRs transferred off-site are utilized in the same manner as self-
generated paper recycling residuals i.e., they are legitimately burned
for fuel in solid fuel boilers that are designed to burn wet fuels,
with mills optimizing their operation around boiler design. Thus, we
have determined that such use does not constitute discard.
    While the EPA agrees that, under certain circumstances, PRRs may be
transferred as a product fuel within the paper recycling industry (and
are not discarded), the Agency disagrees with the comment's
characterization of the AMC I case. AMC I does not directly apply in
this instance. The AMC I holding stated that material reclaimed in a
continuous industrial process could not be a waste. It did not
specifically cover materials transferred between facilities, even in
the same industry, particularly a material reclaimed from recycled
paper but then used for another purpose--burning as a fuel.
    Comment: PRRs are an important part of the fuel mix for facilities
other than paper recycling mills, and third party sellers and
purchasers classify PRR as fuel. Limiting the ability to utilize PRRs
as fuel to those paper mills that have on-site boilers that are
designed to burn solid fuel is arbitrary and unnecessary. Many
facilities routinely purchase and transport non-hazardous secondary
materials generated at a third party location to their sites for
legitimate use as fuel. These materials are sourced and purchased as
fuels from others and thereby satisfy the first two legitimacy
criteria: (1) Be handled as a commodity with an established market; and
(2) have sufficient Btu content to support their use as fuel. The third
legitimacy criterion (contain contaminants that are not significantly
higher in concentration than traditional fuel products), is addressed
in the user's air permit rather than in a duplicative non-waste
determination process.
    Several mills have also partnered with local utilities that can use
the PRRs as fuel. Further, requiring an off-site facility to petition
the EPA before it could acquire and burn PRRs will add significant
administrative costs. Small paper mills typically do not have solid-
fuel boilers and therefore look to off-site partners to find
appropriate uses for their PRRs.
    Response: The Agency disagrees that the categorical non-waste
determination should include PRRs combusted at facilities that are not
paper recycling mills, and lacks sufficient information to determine
that combustors outside the paper recycling industry continue to meet
the legitimacy criteria and are, therefore, not discarded.
    The Agency clearly stated its need for additional information
regarding residuals that are burned as fuel at facilities not under the
control of the generator. The EPA requested detailed information about
how PRRs are managed as a valuable commodity (from point of generation
at the paper recycling mill to insertion at the off-site combustor);
have a meaningful heating value; and contain contaminants at levels
comparable to or lower than those in traditional fuel(s) which the
combustor is designed to burn.
    General statements that PRRs are an important part of the fuel mix
outside the paper recycling industry, and that third party sellers and
purchasers classify PRRs as fuel, is not the relevant consideration for
deciding whether material, even a fuel, is burned as a waste.
    Moreover, merely saying that a material is considered a fuel does
not address the issue of whether that fuel is a waste. Wastes may be
burned as fuels, but they still are wastes. The commenters did not
provide data regarding how that material meets other legitimacy
criteria including management of the fuel as a valuable commodity and
meaningful heating value. In particular, the Agency did not receive
information that facilities outside the paper recycling industry
combusted PRRs in the solid fuel boilers designed to burn wet fuels
characteristic of paper recyclers. While the EPA may accept the low Btu
value of PRRs as a legitimate product fuel for paper recycling
facilities, the same kind of low Btu value fuel could be a waste at
other facilities. At those facilities, any low Btu value material could
simply be thrown in as a waste.
    In addition, the EPA rejects arguments that the Agency should rely
on air permit emissions limitations in determining whether material is
a waste. Prior to establishing emission limits, the EPA first needs to
determine whether the material is discarded in order to decide whether
boiler emission standards (under CAA section 112 regulations) or CAA
section 129 standards would apply.

    PRRs sent off-site for combustion to facilities outside the paper
recycling industry will require submittal and approval of a non-waste
petition under 40 CFR 241.3(c) to be burned at CAA section 112
facilities.
    Comment: The EPA should include cement kilns as an appropriate off-
site end-user for utilization of PRR categorical non-waste fuels.
Cement kilns are capable of handling a wide variety of fuels without
the need for extensive processing that some other combustion facilities
require in order for the materials to be legitimate. A table comparing
the contaminant levels in PRRs to those found in the solid traditional
fuels used at cement kilns, including coal and coke was provided.\99\
The table shows that contaminant concentrations in the PRR categorical
non-wastes are less than the range maximum for coal and coke, which are
the solid traditional fuels used in cement kilns. Meaningful heating
values of 3,700 Btu/lb are also well within the design and operating
range of cement kilns. Some kilns inject water for NOX
control and the same effect could be achieved using a high moisture
fuel material. There is variation in the capabilities and other
environmental restrictions of facilities capable of using PRR
categorical non-waste fuels, and cement kilns in particular generally
have the ability to use a wider variety of fuels. These materials have
great value to the energy intensive cement industry, which manages
alternative fuels as valuable commodities.
---------------------------------------------------------------------------

    \99\ Included in the docket for the final rule.
---------------------------------------------------------------------------

    Response: The Agency disagrees that the categorical non-waste
determination should include PRRs transported offsite and combusted at
cement kilns. The information presented on cement kilns lacks
sufficient detail overall to determine that such PRRs continue to meet
the legitimacy criteria and are not discarded. The information that was
received included the referenced table showing that contaminant
concentrations in the PRRs combusted in cement kiln are less than the
range for solid fuels, as well as cement kilns overall capability to
use a wide range of materials with lower heating values that may not be
practical in other combustion processes. However, no information was
provided, as requested, as to how PRRs are managed as a valuable
commodity from the point of generation at the paper recycling mill to
insertion at the off-site combustor (i.e., cement kiln) to clearly show
that discard is not occurring.
    The arguments that cement kilns are capable of handling a wide
variety of fuels without the need for extensive processing that some
other facilities require and that processing needs to be flexible and
appropriate to the receiving combustion unit could demonstrate that
cement kilns can burn waste fuels as well as non-waste fuels. The
commenter also misunderstands the ``processing'' requirements under 40
CFR part 241 standards. Under 40 CFR 241.3(b)(4), when discarded, NHSMs
must be processed i.e., ``transformed'' into a non-waste fuel, in
accordance with the processing definition at 40 CFR 241.2, and meet
legitimacy criteria prior to combustion. The capabilities of the
combustion unit are not a factor in determining whether the material
has been sufficiently processed.
    To reiterate, these comments generally confirm that cement kilns
are capable of burning wastes as fuels. If they do, they should be
regulated under section 129 of the Clean Air Act.
b. Definition of PRRs
    Comment: The EPA proposes to define PRRs as follows: ``Paper
recycling residuals means the co-product material generated from the
paper recycling process and is composed primarily of wet strength and
short wood fibers that cannot be used to make new paper and paperboard
products. The term paper processing residuals also includes fibers from
old corrugated container rejects.'' Proposed 40 CFR 241.2.
    It is our understanding that the EPA does not intend to distinguish
between residuals from recycling paper and residuals from recycling old
corrugated containers and that the EPA recognizes that these residuals
are composed primarily of fibers but that there could include other
materials from the paper and corrugated cardboard bales. As the EPA has
noted: ``For example, use of old corrugated cardboard (OCC) rejects
(clay, starches, other filler and coating materials, as well as fiber)
are not discarded when used within the control of the generator, since
these secondary materials are part of the industrial process. OCC
rejects can include, and are usually burned in conjunction with, other
fuels (such as bark) at pulp and paper mills that recycle fibers. 76 FR
at 15472.
    To apply this understanding to both paper and paperboard, we
suggest the following revision to the definition: Paper recycling
residuals means the co-product material generated from the recycling of
paper, paperboard, and corrugated containers and is composed primarily
of wet strength and short wood fibers that cannot be used to make new
paper and paperboard products.
    Response: The EPA disagrees that the definition of PRR should not
distinguish between wet strength and short wood fibers and the non-
fiber material contained in OCC rejects (clays, starches, and other
filler and coating additives) as well as other non-fiber material
(polystyrene foam, polyethylene film, other plastics, waxes and
adhesives, dyes and ink). As discussed in section V.B.4. of this
preamble, the Agency finds that PRRs that are not composed primarily of
wood fibers unsuitable for making paper and contain more than small
amounts of certain non-fiber materials would be considered waste fuels
and would not be eligible for this categorical listing.
    As discussed in the comment above regarding meaningful heating
value, no specific information was received from industry regarding the
percentage of these non-fiber materials as the Agency requested.
Lacking information to the contrary, the Agency finds that PRRs with
higher amounts of non-fiber materials would have a lower heating value.
Combustion of materials with low heating values would be considered
discard of those materials and burning of a waste fuel. The Agency is
thus revising the proposed definition of PRRs and clarifying the
previous statements at 76 FR 15472, March 21, 2011, regarding non-fiber
material contained in OCC rejects to make clear that the categorical
non-waste listing applies only to PRRs composed primarily of wet
strength and short wood fibers that do not contain more than small
amounts of polystyrene foam, polyethylene film, other plastics, waxes
and adhesives, dyes and ink clays, starches, and other filler and
coating additives.
    The definition also clarifies that PRRs are more appropriately
defined as secondary materials \100\ rather than co-products, generated
from the recycling of paper, paperboard and corrugated containers. Use
of the term co-products could infer that PRRs are a product fuel that
has undergone processing through the paper recycling manufacturing
process. Rather, the paper recycling manufacturing process primarily
makes wood fibers that are used to make new paper and paperboard
products. PRRs are a secondary material or ``byproduct'' of that
manufacturing process and are not discarded when used as a fuel within
control of the generator or sent off-site to other paper recycling
mills within the industry and legitimately

burned in solid fuel boilers that are designed to burn wet fuels.
---------------------------------------------------------------------------

    \100\ Secondary materials are materials that are not the primary
product of a manufacturing or commercial process, and can include
post-consumer material, off-specification commercial chemical
products or manufacturing chemical intermediates, post-industrial
material and scrap.
---------------------------------------------------------------------------

    The revised definition of Paper recycling residuals at 40 CFR 241.2
appears in the regulatory language at the end of this document.

C. Creosote-Treated Railroad Ties (CTRTs)

    The April 14, 2014 proposed rule described CTRTs in detail,
explained the status of CTRTs under current rules, discussed comments
received during previous proceedings, and discussed the scope of the
proposed non-waste listing (79 FR 21021-23). The proposed rationale for
the listing is found in the proposal at 79 FR 210 23-28 and is
summarized and incorporated into this final rule, along with all
sources referenced in that discussion and cited therein. The final
decision in this rule is based on the information in the proposal and
supporting materials in the rulemaking record. Any changes made to the
final rule are based on the rationale, as described below.
1. Detailed Description of CTRTs
    Railroad ties are typically comprised of North American hardwoods
that have been treated with creosote. Creosote was introduced as a wood
preservative in the late 1800's to prolong the life of railroad ties.
Creosote-treated wood ties remain the material of choice by railroads
due to their long life, durability, cost effectiveness, and
sustainability. As creosote is a by-product of coal tar distillation,
and coal tar is a by-product of making coke from coal, creosote is
considered a derivative of coal. The creosote component of CTRTs is
governed by the standards established by the American Wood Protection
Association (AWPA). AWPA has established two blends of creosote, P1/13
and P2.\101\ Railroad ties are typically manufactured using the P2
blend that is more viscous than other blends.
---------------------------------------------------------------------------

    \101\ AWPA Standard P1/P13 and P2 provide specifications for
coal-tar creosote used for preservative treatment of piles, poles
and timber for marine, land and freshwater use. The character of the
tar used, the method of distillation, and the temperature range in
which the creosote fraction is collected all influence the
composition of the creosote, and the composition may vary with the
requirement of standard specifications. April 2010. Forest Products
Laboratory. 2010 Wood Handbook. General Technical Report FPL_GTR-
190. Madison, WI.
---------------------------------------------------------------------------

    CTRTs are railroad crossties removed from service and processed
prior to being used as a fuel. Approximately 17 million crossties are
removed from service each year. About one third of the removed CTRTs
are used for landscaping, with the majority of the remaining two thirds
used for energy recovery. Because of its high energy content, CTRTs can
be used for heat and energy recovery in combustion units as a
nonhazardous biomass alternative to fossil fuel.\102\
---------------------------------------------------------------------------

    \102\ American Forest & Paper Association, American Wood
Council--Letter to EPA Administrator, December 6, 2012.
---------------------------------------------------------------------------

    Most of the energy recovery with crossties is conducted through
three parties: The generator of the crossties (railroad or utility);
the reclamation company that sorts the crossties, and in some cases
processes the material received from the generator; \103\ and the
combustor as third party energy producers. Typically, ownership of the
crossties is transferred directly from the generator to the reclamation
company that sorts materials for highest value secondary uses, and then
sells the products to end-users, including those combusting the
material as fuel. Some reclamation companies sell CTRTs to processors
who remove metal contaminants and grind the ties into chipped wood.
Other reclamation companies have their own grinders, do their own
contaminant removal, and can sell directly to the combusting
facilities. Information submitted to the Agency states there are
approximately 15 CTRT recovery companies in North America with industry
wide revenues of $65-75 million. Members of AF&PA report that the value
of CTRTs is underscored by the approximately $20-$30 per ton paid for
CTRTs which can sometimes be a premium price compared to certain hog
fuels (untreated clean wood residues from sawmills).\104\
---------------------------------------------------------------------------

    \103\ In some cases, the reclamation company sells the crossties
to a separate company for processing.
    \104\ American Forest & Paper Association, American Wood
Council--Letter to EPA Administrator, December 6, 2012.
---------------------------------------------------------------------------

    After crossties are removed from service, they are transferred for
sorting/processing, but in some cases, they may be temporarily stored
in the railroad rights-of-way or at another location selected by the
reclamation company. One information source stated that when the
crossties are temporarily stored, they are stored until their value as
an alternative fuel can be realized, generally through a contract
completed for transferal of ownership to the reclamation contractor or
combustor.\105\ This means that not all CTRTs originate from crossties
removed from service in the same year; some CTRTs are processed from
crossties removed from service in prior years and stored by railroads
or removal/reclamation companies until their value as a landscaping
element or fuel could be realized.
---------------------------------------------------------------------------

    \105\ M.A. Energy Resources LLC, Petition submitted to
Administrator, EPA. February 2013.
---------------------------------------------------------------------------

    CTRTs are transferred to reclamation companies, typically by rail.
The processing of the crossties into fuel by the reclamation/processing
companies involves several steps. Metals (spikes, nails, plates, etc.)
are removed using a magnet, occurring one or several times during the
process. The crossties are then ground or shredded to a specified size
depending on the particular needs of the end-use combustor, with chip
size typically between 1-2 inches. This step occurs in several phases,
including primary and secondary grinding, or in a single phase. Once
the crossties are ground to a specific size, additional metal is
removed if present and there is further screening based on the
particular needs of the end-use combustor. Depending on the
configuration of the facility and equipment, screening occurs
concurrently with grinding or at a subsequent stage. Throughout the
process, a non-toxic surfactant is applied to the crossties being
processed to minimize dust.
    Once the processing of CTRTs is complete, the CTRTs are sold
directly to the end-use combustor for energy recovery. Processed CTRTs
are delivered to the buyers by railcar or truck. The CTRTs are then
stockpiled prior to combustion, with storage timeframes ranging from a
day to a week. When the CTRTs are to be burned for energy recovery, the
material is then transferred from the storage location using a conveyor
belt or front-end loader. The CTRTs are combined with other biomass
fuels, including hog fuel and bark. CTRTs are used to provide high Btu
fuel to supplement low (and sometimes wet) Btu biomass to ensure proper
combustion, often in lieu of coal or other fossil fuels.\106\ The
combined fuel may be further hammered and screened prior to combustion.
Contracts for the purchase and combustion of CTRTs may include fuel
specifications limiting contaminants, such as metal, and precluding the
receipt of wood treated with preservatives other than creosote.
---------------------------------------------------------------------------

    \106\ American Forest & Paper Association, American Wood
Council--Letter to EPA Administrator, December 6, 2012.
---------------------------------------------------------------------------

2. CTRTs Under Previous NHSM Rules
a. March 21, 2011 NHSM Final Rule
    The March 21, 2011 NHSM final rule stated that most creosote-
treated wood is non-hazardous. However, the presence of
hexachlorobenzene, a CAA section 112 HAP, as well as other HAP
suggested that creosote-treated wood, including CTRTs, contained

contaminants at levels that are not comparable to or lower than those
found in wood or coal, the fuel that creosote-treated wood would
replace. In making the assessment, the Agency did not consider fuel oil
\107\ as a traditional fuel that CTRTs would replace, and concluded at
the time that combustion of creosote-treated wood may result in
destruction of contaminants contained in those materials. Such
destruction is an indication of incineration, a waste activity.
Accordingly, creosote-treated wood, including CTRTs when burned, seemed
more like a waste than a commodity, and did not meet the contaminant
legitimacy criterion. This material, therefore, was considered a solid
waste when burned and units combusting it would be subject to the CAA
section 129 emission standards. The conclusions from the March 21, 2011
rule regarding creosote-treated wood are discussed further in section
V.C.4. of this preamble.
---------------------------------------------------------------------------

    \107\ For the purposes of this final rule, fuel oil means oils
1-6, including distillate, residual, kerosene, diesel, and other
petroleum based oils. It does not include gasoline or unrefined
crude oil.
---------------------------------------------------------------------------

b. February 2013 NHSM Final Rule
    In the February 7, 2013 NHSM final rule, the EPA noted that AF&PA
and the American Wood Council submitted a letter with supporting
information on December 6, 2012, seeking a categorical listing for CTRT
combusted in any unit. The letter included information regarding the
amounts of railroad ties combusted each year and the value of the ties
as fuel. The letter also discussed how CTRTs satisfy the legitimacy
criteria, including its high Btu value.
    While this information was useful, it was not sufficient for the
EPA to propose that CTRTs be listed categorically as a non-waste fuel.
As explained in the proposed rule, the EPA had requested that
additional information be provided to further inform the Agency as to
whether to list CTRTs categorically as a non-waste fuel, and stated
that if this additional information supported and supplemented the
representations made in the December 2012 letter, the EPA would expect
to propose a categorical listing for CTRTs.
    The requested information and responses provided are outlined
below.
     A list of industry sectors, in addition to forest product
mills, that burn railroad ties for energy recovery: One respondent
claimed that a number of end-use combustors utilize CTRTs as an
alternative fuel to offset fossil fuel at all times. Such facilities
use as much as 100-500 tons of CTRTs daily. The respondent also claimed
to know of additional end-use combustors that utilize CTRTs
occasionally based on availability and cost. Furthermore, the
respondent was aware of other end-use combustors that are operationally
able to utilize CTRTs as an alternative fuel to offset fossil fuel, but
have chosen not to use CTRTs as a result of the current solid-waste
implications associated with CTRTs. The end-use combustors that
currently utilize CTRTs, both full-time and part-time, represent a
variety of industry sectors, including pulp and paper manufacturing,
cogeneration plants, utilities, and chemical manufacturing facilities.
For the utility sector, at least 14 utilities could burn (i.e., are
permitted to burn) or are burning CTRTs.\108\ Another respondent
claimed that data \109\ show that a number of forest product mills are
currently using railroad ties as a fuel and that other mills are
permitted to burn these materials as fuels, but have stopped using them
as a fuel due to their uncertain regulatory status, as well as other
economic factors (e.g., lower cost of other fuels).
---------------------------------------------------------------------------

    \108\ Information received subsequent to the request for data in
the February 13, 2013 rule discussed above claims that 14 entities
in the utility sector could burn (i.e., are permitted to burn) or
are burning cross-tie derived fuel (i.e., CTRTs). Of the 14
entities, 9 companies are currently firing or have fired CTRTs
within the past two years. Information on pulp and paper and utility
sources currently utilizing CTRTs demonstrates that several of these
sources use between 5,000 and 70,000 tons of CTRTs per year.
Information compiled by M.A. Energy LLC. (MAER) contained in letters
and emails from All4 Inc. to EPA dated January 29, and February 28,
2014.
    \109\ American Forest and Paper Association and American Wood
Council's letter to George Faison, EPA. March 7, 2013.
---------------------------------------------------------------------------

     The types of boilers (e.g., kilns, stoker boilers,
circulating fluidized bed, etc.) that burn railroad ties for energy
recovery. Respondents stated that the types of units operated by those
end-use combustors that utilize CTRTs as an alternative fuel include
fluidized bed, traveling grate, and spreader stoker. Forest product
industry boilers that burn railroad ties are generally one of three
types: stoker, bubbling bed or fluidized bed boilers.\110\
---------------------------------------------------------------------------

    \110\ Information was received that the forest products industry
boilers combusting CTRTs also includes hybrid suspension grate
boilers. See docket EPA-HQ-RCRA-2013-0110-0076.
---------------------------------------------------------------------------

     The traditional fuels and relative amounts (e.g., startup,
30 percent, 100 percent) of these traditional fuels that could
otherwise generally be burned in these types of units. Respondents also
claimed that units operated by end-use combustors that utilize CTRTs as
an alternative fuel typically burn a variety of ``traditional fuels,''
such as coal, biomass (i.e., hog fuel, bark fuel, and other biomass
fuel materials), and fuel oil, as well as other materials and wastes,
such as tire derived fuel, waste derived liquid fuel, and waste derived
solid fuel.111 112 In general, they claimed that all of the
units that burn CTRTs also burn significant quantities of biomass given
the similarity of the fuels' characteristics. In addition, they claimed
that most of these units are permitted to burn fuel oil either during
start-up or during normal operations. The respondents claimed that many
factors determine how much fuel oil is burned. For example, because
natural gas prices are low, natural gas is often the fuel of choice, if
available. In addition, they claimed that some states are looking to
reduce SO2 emissions from sources and thus, encourage
greater use of biomass or natural gas rather than fuel oil.\113\
---------------------------------------------------------------------------

    \111\ To the extent that any of these boilers burn fuel derived
from waste, or any other solid waste, they would be subject to the
CAA section 129 CISWI standards, and the Agency's rule in this
document would not impact their regulatory status.
    \112\ American Forest and Paper Association and American Wood
Council's letter to George Faison, EPA. March 7, 2013.
    \113\ Examples of combustors utilizing a variety of traditional
and other fuels, including facilities combusting both CTRTs and fuel
oil, is found in documentation provided by the American Associations
of Railroads (AAR). The document listed 11 non- pulp and paper
facilities including power generators. All of the facilities listed
combust CTRTs, three facilities combust CTRT and fuel oil, three
facilities combust CTRT and natural gas. Other fuels combusted
include tire-derived fuel, and landfill gas. February 2013.
---------------------------------------------------------------------------

    Respondents claimed that the most comparable traditional fuel to
railroad ties is fuel oil. However, they believe the question of
whether a combustion unit is designed to burn a specific fuel is not
relevant when the EPA makes a determination under 40 CFR 241.4(a).
Specifically, the respondents claimed that the EPA has interpreted the
phrase ``designed to burn'' to mean that a combustor that burns NHSMs
as a non-waste fuel has to be able to burn the NHSM in the combustion
unit, which in the case of CTRTs, would require the installation of a
nozzle for the delivery of liquid fuel into the boiler, to meet the
contaminant legitimacy criterion. The EPA explained that this standard
is to avoid the possibility that discard could be occurring in some
situations.\114\ However, in the context of a specific non-waste
determination under 40 CFR 241.4(a), the respondents argued that the
EPA has the opportunity to evaluate all the factors relating to the use
of CTRTs as a fuel, including the fact that CTRTs is a commodity that
is purchased by the combustor. Furthermore, respondents argued that the
EPA has the

discretion to recognize that when a combustor purchases CTRTs and then
burns it in a boiler, that combustion is for the purpose of generating
energy rather than discarding the railroad ties. According to the
respondents, any other conclusion would lead to the absurd result that
one boiler can burn CTRTs as a legitimate fuel and another boiler--with
essentially the same design except for a nozzle feed for fuel oil--
would have to consider the CTRTs as a solid waste. (See section V.B.6
of this preamble for the EPA's consideration of the information and
views presented by these respondents.)
---------------------------------------------------------------------------

    \114\ See 78 FR 9149
---------------------------------------------------------------------------

     The extent to which non-industrial boilers (e.g.,
commercial or residential boilers) burn CTRTs for energy recover. The
respondent understood that the residential use of CTRTs for purposes of
energy recovery is unlikely. However, they explained that several local
utilities in the northern Midwest utilize CTRTs for purposes of power
generation but they have not identified the specific facilities.
     Laboratory analyses for contaminants known or reasonably
suspected to be present in creosote-treated railroad ties, and
contaminants known to be significant components of creosote,
specifically polycyclic aromatic hydrocarbons (i.e., PAH-16),
dibenzofuran, cresols, hexachlorobenzene, 2,4-dinitrotoluene, biphenyl,
quinoline, and dioxins.\115\ Respondents submitted contaminant data for
crushed CTRTs, which are discussed in section V.C.4. of this preamble.
With the exception of dioxins, which respondents explain will not be
present in CTRTs, analyses were submitted for all requested
constituents and other contaminants.
---------------------------------------------------------------------------

    \115\ The Agency requested these analyses based on the limited
information previously available concerning the chemical makeup of
CTRTs. That limited information included one well-studied sample
from 1990 (showing the presence of both PAHs and dibenzofuran), past
TCLP results (which showing the presence of cresols,
hexachlorobenzene and 2,4-dinitrotoluene), Material Safety Data
Sheets for coal tar creosote (which showing the potential presence
of biphenyl and quinoline), and the absence of dioxin analyses prior
to combustion despite extensive dioxin analyses of post-combustion
emissions.
---------------------------------------------------------------------------

3. Scope of the Proposed Rule and Final Categorical Non-Waste Listing
for CTRT
    Under the proposed rule, CTRT was proposed to be listed as a
categorical non-waste when combusted in units that burn both fuel oil
and biomass. This limitation was based on the fact that contaminant
levels for semi-volatile organics (SVOCs) are significantly higher in
CTRT than levels in biomass and coal, but CTRT levels for those
contaminants are lower than levels in fuel oil. In contrast, fluorine
and nitrogen contaminant levels are significantly higher in CTRT than
in fuel oil, but levels for those contaminants are lower than levels in
biomass and coal (79 FR 21023.) Thus, only units burning both biomass
and fuel oil would pass the contaminant legitimacy criteria when
comparing contaminants in the NHSM to the traditional fuel.
    Based on information received after the February 7, 2013 final rule
stating that units were switching from fuel oil to natural gas due to
lower compliance costs during operation, we also stated in the proposal
that the Agency was considering another approach for CTRTs combusted in
existing units at major source pulp and paper mills that had been
designed to burn fuel oil and biomass, but are being modified in order
to use clean fuel such as natural gas instead of fuel oil (79 FR
21028). If the EPA were to include this additional approach in the
categorical listing, the CTRT could continue to be combusted only if
certain conditions were met, which are all intended to ensure that the
CTRTs are not being discarded. Conditions included in the proposal are:
     CTRTs must be burned in an existing stoker, bubbling bed
or fluidized bed boiler;
     the CTRTs can comprise no more than 40 percent of the fuel
that is used on a monthly basis; \116\
---------------------------------------------------------------------------

    \116\ Statements at meeting between American Forest and Paper
Association and Mathy Stanislaus on December 19, 2013 indicate that,
CTRTs generally comprise 40% of total fuel load.
---------------------------------------------------------------------------

     the boiler that burned the CTRTs must have been designed
to burn both fuel oil and biomass; and
     boiler is modifying its design to also burn natural gas.
    The Agency stated in the proposed rule that we did not believe that
combustion of CTRT in boiler units that are currently designed to burn
both biomass and fuel oil but are being modified (i.e., removing oil
delivery equipment) in order to burn natural gas should be considered
discard of the CTRTs. EPA considered that these facilities have
demonstrated the ability to burn fuel oil along with biomass and should
not be penalized for switching to the cleaner natural gas fuel.
Information submitted at the time indicating that CTRTs are an
important part of the fuel mix due to the consistently lower moisture
content and higher Btu value, as well as the benefits of drier, more
consistent fuel to combustion units with significant swings in steam
demand, further suggested that discard is not occurring.
    The additional approach was meant to address only the circumstance
where contaminants in CTRTs are comparable to or less than the
traditional fuels the unit was originally designed to burn (both fuel
oil and biomass) but that design was modified in order to combust
natural gas. The approach was not a general means to circumvent the
contaminant legitimacy criterion by allowing combustion of any NHSM
with elevated contaminant levels, i.e. levels not comparable to the
traditional fuel the unit is currently designed to burn. The particular
facilities in this case had used CTRTs and would clearly be in
compliance with the legitimacy criteria if they did not switch to the
cleaner natural gas fuel. EPA believed it appropriate to balance other
relevant factors in this categorical non-waste determination and that
it is appropriate for the Agency to decide that the switching to the
cleaner natural gas would not render the CTRTs a waste fuel in view of
the historical usage as a product fuel in the stoker, bubbling bed and
fluidized bed boilers.
    For this final rule, based on comments received and information in
the rulemaking record, the EPA has sufficient information to list CTRTs
as a categorical non-waste fuel in combustion units that are designed
to burn both biomass and fuel oil. The Agency finds that units will
meet this condition if the unit combusts fuel oil as part of normal
operations and not solely as part of start-up or shut-down operations.
    The Agency is also adopting the additional approach outlined in the
proposed rule with some revisions. Specifically, based on comments
received and information in the rulemaking record, the Agency has
sufficient information to list as categorical non-wastes CTRTs that are
combusted in units at major source pulp and paper mills or power
producers subject to 40 CFR part 63 Subpart DDDDD (Boiler MACT) that
had been designed to burn biomass and fuel oil, but are modified (e.g.
oil delivery mechanisms are removed) in order to use natural gas
instead of fuel oil as part of normal operations and not solely as part
of start-up or shut-down operations. The CTRT may continue to be
combusted as a product fuel under this section only if certain
conditions are met, which are intended to ensure that the CTRTs are not
being discarded:
     The CTRTs must be combusted in existing (i.e. commenced
construction prior to April 14, 2014) stoker, bubbling bed, fluidized
bed or hybrid suspension grate boilers; and

     CTRTs can comprise no more than 40 percent of the fuel
that is used on an annual heat input basis.
    The standard is applicable to existing units burning CTRTs that had
been designed to burn fuel oil and biomass and have been modified to
burn natural gas. The standard will also apply if an existing unit
burning CTRTs and designed to burn fuel oil and biomass is modified at
some point in the future.
    Based on comments received on the proposed rule, several revisions
were made in the additional approach as adopted for the final rule
under section 241.(a)(7): (1) CTRTs combusted in units at power
producers subject to 40 CFR part 63 Subpart DDDDD (Boiler MACT) have
been added to the categorical listing; (2) the 40% fuel load limit has
been changed to an annual heat input basis; (3) regulatory language was
added stating that units combusting fuel oil and natural gas, as well
as units that had switched from fuel oil to natural gas, must combust
these materials as part of normal operations and not solely as part of
start-up or shut-down operations; and (4) hybrid suspension grate
boilers are added to the list of acceptable boilers and to provide
further clarity regarding CTRTs combusted in ``existing'' stoker,
bubbling bed, fluidized bed or hybrid suspension grate boilers,
existing is defined as April 14, 2014, the date of issuance of the
proposed rule.
    See section V.C.6. Response to Comments for a further discussion of
these changes.
4. Rationale for Final Rule
    This section discusses the reasoning provided in the proposed rule
and the reasons for the EPA's final determinations for the categorical
listing of CTRTs. EPA adopts the reasoning in the proposed rule and
further explains it in this preamble. Further explanations for the
Agency's decision are provided in the Response to Comments below. The
proposal, this section, and the Response to Comments all constitute the
Agency's final determination supporting this rule.
a. Discard
    When deciding whether an NHSM should be listed as a categorical
non-waste fuel in accordance with 40 CFR 241.4(b)(5), the EPA first
evaluates whether or not the NHSM has been discarded in the first
instance and, if not so discarded, whether or not the material could be
considered discarded because it is not legitimately used as a product
fuel in a combustion unit. Based on the rulemaking record, as discussed
below, the Agency has determined that CTRTs are not discarded when
processed and combusted in the types of units described herein.
i. Storage of CTRT
    As discussed in section V.C.1. of this preamble, crossties removed
from service are sometimes temporarily stored in the railroad right-of-
way or at another location selected by the reclamation company. This
means that not all CTRTs originate from crossties removed from service
in the same year; some CTRTs are processed from crossties removed from
service in prior years and stored by railroads or removal/reclamation
companies until a contract for reclamation is in place.
    The December 6, 2012, letter from AF&PA states that in those cases
where the railroad or reclamation company wait for more than a year to
realize the value of the CTRTs as a fuel (or in landscaping) does not
mean that the CTRTs have been discarded and cite 76 FR 15456, 15520 of
the March 21, 2011 rule. That section of the rule addresses the
management of the NHSM as a valuable commodity and states that storage
of the NHSM must be within a reasonable timeframe.\117\ The letter
further states that there is a robust market for companies engaged in
railroad tie reclamation, and the cost of this material indicates that
the material is a valuable commodity and has not been discarded.
---------------------------------------------------------------------------

    \117\ As discussed in the NHSM final rule (76 FR 15520),
``reasonable time frame'' is not specifically defined as such time
frames vary among the large number of non-hazardous secondary
materials and industries involved.
---------------------------------------------------------------------------

    While the Agency recognizes that the reasonable timeframe for
storage may vary by industry, the Agency disagrees that any explanation
(other than a repeat of what the rules say) has been provided of why
storage that may be longer than a year is not discard, especially when
they argue that CTRTs are a valuable material. Therefore, without
further explanation or information from the public, the Agency
concludes that CTRTs removed from service that may be stored in a
railroad right of way or other location for long periods of time--that
is, a year or longer, without a determination regarding their final end
use (e.g., landscaping, as a fuel or land filled) shows that the
material has been discarded and is a solid waste (see the preamble
discussion of discard 76 FR 15463 in the March 21, 2011 rule). The
assertion that the CTRTs are a valuable commodity in a robust market
does not change the fact that the CTRTs have been discarded at some
point. NHSMs may have value in the marketplace and still be wastes.
ii. Processing of CTRTs
    The railroad ties removed from service are considered discarded
because they can be stored for long periods of time without a final
determination regarding their final end use. In order for them to be
considered a non-waste fuel, they must be processed, thus transforming
the railroad ties into a product fuel that meets the legitimacy
criteria, or if not meeting the legitimacy criteria, would still be
considered a non-waste fuel if the EPA decides so after balancing the
legitimacy criteria with other relevant factors. The Agency concludes
that the processing of CTRTs described above in section V.C.1. of this
preamble meets the definition of processing in 40 CFR 241.2. Processing
includes operations that transform discarded NHSM into a non-waste fuel
or non-waste ingredient, including operations necessary to: Remove or
destroy contaminants; significantly improve the fuel characteristics
(e.g., sizing or drying of the material, in combination with other
operations); chemically improve the as-fired energy content; or improve
the ingredient characteristics. Minimal operations that result only in
modifying the size of the material by shredding do not constitute
processing for the purposes of the definition. Specifically, the Agency
concludes that CTRTs meet the definition of processing in 40 CFR 241.3
because:
     Contaminants (spikes, nails, plates, etc.) are removed
using a magnet. This magnetic removal of metals may occur several times
during processing.
     The fuel characteristics of the material are improved when
the crossties are ground or shredded to a specified size depending on
the particular needs of the end-use combustor. The grinding may occur
in one or more phases. Once the CTRTs are ground, there may be
additional screening to bring the material to a specified size.
b. Legitimacy Criteria
    In determining whether to list CTRTs as a categorical non-waste
fuel in 40 CFR 241.4(a), the Agency evaluated the legitimacy criteria
in 40 CFR 241.3(d)(1)--that is, whether it is managed as a valuable
commodity, whether it has a meaningful heating value and is used as a
fuel in a combustion unit to recover energy, and whether contaminants
or groups of contaminants are at levels comparable to or less than
those in the traditional fuel the unit is designed to burn. To the
extent that CTRTs do not meet one or more of the legitimacy criteria,
and are

thus discarded, the Agency may consider other relevant factors in
determining whether to list CTRT as a categorical non-waste fuel (40
CFR 241.4(b)(5)(ii)). The Agency adopts for the final rule the
reasoning explained below.
i. Managed as a Valuable Commodity
    As discussed in the proposed rule and adopted for the final rule,
the processing of CTRTs is correlated to the particular needs of the
end-use combustor. Additional screening may take place after the
grinding and shredding of the CTRTs if deemed necessary. Once the CTRTs
meet the end use specification, they are then sold directly to the end-
use combustor for energy recovery. CTRTs are delivered to the end-use
combustors via railcar and/or truck similar to delivery of traditional
biomass fuels. While awaiting combustion at the end-user, which usually
takes place within a week of arrival, the CTRTs are transferred and/or
handled from storage in a manner consistent with the transfer and
handling of biomass fuels. Such procedures include screening by the
end-use combustor, combining with biomass fuels, and transferring to
the combustor via conveyor belt or front-end loader. Since processed
CTRT storage does not exceed reasonable time frames and are handled/
treated similar to analogous biomass fuels by end-use combustors, CTRTs
meets the criterion for being managed as a valuable commodity.\118\
---------------------------------------------------------------------------

    \118\ Prior to the CTRTs being processed as a product fuel, the
CTRTs are considered solid wastes and would be subject to
appropriate federal, state, and local requirements.
---------------------------------------------------------------------------

ii. Meaningful Heating Value and Used as Fuel To Recover Energy
    As discussed in the proposal and adopted as the reasoning to
support the final rule, the heating value of processed CTRTs ranges
from 6,000-8,000 Btu/lb as fired, and combustion units recover energy
by burning the material as fuel. In the March 21, 2011 NHSM final rule,
the Agency stated that NHSMs with an energy value greater than 5,000
Btu/lb, as fired, are considered to have a meaningful heating
value.\119\ Information compiled by the EPA in 2011 also specifies that
CTRTs could replace clean wood that has an average as-fired heating
value of 5,150 Btu/lb, with a low as-fired heating value of 3,440 Btu/
lb.\120\ Thus, CTRTs have greater heating value than the traditional
fuel it replaces, and meet the criterion for meaningful heating value
and used as a fuel to recover energy, and are not discarded for
purposes of this criterion.
---------------------------------------------------------------------------

    \119\ See 76 FR 15541.
    \120\ Fuel analysis data for unadulterated wood. USEPA, Office
of Air Quality Planning and Standards, Emissions Data for Boilers
and Process Heaters Containing Stack Test, CEM & Fuel Analysis Data
Reported Under ICR No. 2286.03 (Version 6) EPA Docket Number EPA-HQ-
OAR-2002-0058-3255. February 2011.
---------------------------------------------------------------------------

iii. Contaminants Comparable to or Lower Than Traditional Fuels
    For CTRTs, the EPA compared the additional data submitted on
contaminant levels by industry to analogous data for two traditional
fuels: Biomass (including untreated clean wood) and fuel oil. The data
the EPA received on CTRTs comes from the following three sources: M.A.
Energy Resources (MAER), URS Corporation on behalf of the Association
of American Railroads, and AF&PA. The information submitted by MAER
included a comprehensive analysis of one CTRT sample. The sample came
from a CTRT pile located at an end-use combustor. The URS Corporation
report included three samples of processed CTRTs from the National
Salvage facility in Selma, Alabama, and from a Stella Jones facility in
Duluth, Minnesota. AF&PA also submitted documents comparing contaminant
concentrations in CTRTs with traditional fuels, compiling data from
various sources in these documents. The EPA considers data from these
eight facilities to be representative of the CTRT universe because the
composition of the creosote component of the CTRTs is the same--that
is, the P2 blend of creosote, as well as the fact that multiple samples
have been taken in different parts of the country at different points
in the CTRT management chain.
    The section below discusses determinations on contaminant
comparisons in CTRTs to fuel oil and biomass. The contaminant data
received on CTRTs includes information that units combusting CTRTs and
fuel oil may also combust coal; determinations regarding contaminant
comparisons to that traditional fuel follows the discussion on fuel oil
and biomass.
    Contaminant Comparisons in CTRTs to Fuel Oil and Biomass. Table 3
of this preamble lists the aggregated CTRT data received as it compares
to contaminants found in two traditional fuels that industry claim are
used, in varying amounts, at facilities burning processed CTRTs for
energy recovery.

                             Table 3--Contaminant Ranges in Traditional Fuels & CTRT
                                             [In parts per million]
----------------------------------------------------------------------------------------------------------------
         Contaminant                  Biomass \a\                Fuel oil \a\                  CTRT \b\
----------------------------------------------------------------------------------------------------------------
                                                 Metal Elements
----------------------------------------------------------------------------------------------------------------
Antimony (Sb)...............  ND-26.....................  ND-15.7...................  ND
Arsenic (As)................  ND-298....................  ND-13.....................  ND-3.2
                                                                                ND
Beryllium (Be)..............  ND-10.....................  ND-19.....................  ND-0.3
Cadmium (Cd)................  ND-17.....................  ND-1.4....................  ND-0.3
Chromium (Cr)...............  ND-340....................  ND-37.....................  ND-15.3
Cobalt (Co).................  ND-213....................  ND-8.5....................  ND
Lead (Pb)...................  ND-340....................  ND-56.8...................  ND-9.6
Manganese (Mn)..............  ND-15,800.................  ND-3,200..................  63-185
Mercury (Hg)................  ND-1.1....................  ND-0.2....................  0.02-0.05
Nickel (Ni).................  ND-540....................  ND-270....................  ND-38
Selenium (Se)...............  ND-9......................  ND-4......................  ND-1
----------------------------------------------------------------------------------------------------------------
                                               Non-Metal Elements
----------------------------------------------------------------------------------------------------------------
Chlorine (Cl)...............  ND-5,400..................  ND-1,260..................  22-400
Fluorine (F)................  ND-300....................  ND-14.....................  100
Nitrogen (N)................  200--39,500...............  42-8,950..................  1,600-14,400

Sulfur (S)..................  ND-8,700..................  ND-57,000.................  681-3,277
----------------------------------------------------------------------------------------------------------------
                            Volatile Organic Compound (VOC) Hazardous Air Pollutants
----------------------------------------------------------------------------------------------------------------
Benzene.....................  ..........................  ND-75.....................  ND
Phenol......................  ..........................  ND-7,700..................  ND
Styrene.....................  ..........................  ND-320....................  ND
Toluene.....................  ..........................  ND-380....................  ND
Xylenes.....................  ..........................  ND-3,100..................  0.325
Cumene......................  ..........................  6,000-8,600...............  ND
Ethyl benzene...............  ..........................  22-1270...................  0.058
Formaldehyde................  1.6-27....................  ..........................  ND
Hexane......................  ..........................  50-10,000.................  ND
15 Additional VOC...........  ..........................  ..........................  ND
                             -----------------------------------------------------------------------------------
    Total VOC \c\...........  1.6-27....................  6,072-19,810..............  0.383
----------------------------------------------------------------------------------------------------------------
                                        Semivolatile Hazardous Pollutants
----------------------------------------------------------------------------------------------------------------
Biphenyl....................  ..........................  1,000-1,200...............  137-330
16-PAH \d\..................  ..........................  3,900-54,700..............  6641-21,053
Dibenzofuran................  ..........................  ..........................  570-1,500
Quinoline...................  ..........................  ..........................  40.2
Cresols.....................  ..........................  ..........................  1.51
Hexachlorobenzene...........  ..........................  ND........................  ND
2,4-dinitrotoluene..........  ..........................  ND........................  ND
Lindane.....................  ..........................  ..........................  0.238
11 Additional SVOC..........  ..........................  ..........................  ND
                                                         -------------------------------------------------------
    Total SVOC \c\..........  ..........................  4,900-54,700..............  7,618-22,883
----------------------------------------------------------------------------------------------------------------
\a\ ``Contaminant Concentrations in Traditional Fuels: Tables for Comparison'' document available at http://www.epa.gov/epawaste/nonhaz/define/pdfs/nhsm_cont_tf.pdf. Contaminant data drawn from various literature
  sources and from data submitted to USEPA, Office of Air Quality Planning and Standards (OAQPS).
\b\ (1) MA Energy Resources, LLC. February 2013 Crosstie Derived Fuel Petition; (2) URS, Evaluation of Used
  Railroad Ties Treated with Creosote. Prepared for Association of American Railroads. January 28, 2013; (3)
  AF&PA, Comparison of Contaminant Concentrations in Crosstie Derived Fuel with Traditional Fuels. February 28,
  2013.
\c\ Total VOC and SVOC ranges do not represent a simple sum of the minimum and maximum values for each
  contaminant. This is because minimum and maximum concentrations for individual VOCs and SVOCs do not always
  come from the same sample.
\d\ 16-PAH includes: Acenaphthene, acenaphthylene, anthracene, benz(a)anthracene, benzo(a)pyrene,
  benzo(b)fluoranthene, benzo(g,h,i)perylene, benzo(k)fluoranthene, chrysene, dibenz(a,h)anthracene,
  fluoranthene, fluorene, indeno(1,2,3-cd)pyrene, naphthalene, phenanthrene, and pyrene. 16-PAH is designated as
  Total PAH in the Table for Comparison cited in note ``a'' above.

    As shown in Table 3 of this preamble, all contaminant concentration
levels for metals are within the ranges identified for fuel oil and
biomass. We note that when comparing the non-metal elemental
contaminants, however, fluorine and nitrogen levels in CTRTs are not
comparable to fuel oil, and semi-volatile organic compound (SVOC)
levels are not comparable to biomass. Given that CTRTs are a type of
treated wood biomass, and any unit burning CTRTs typically burns
untreated wood, the EPA considered two scenarios that industry
described.
    In the first scenario, where a combustion unit is designed to only
burn biomass, the EPA compared contaminant levels in CTRTs to
contaminant levels in biomass. In this scenario, the total SVOC levels
can reach 22,883 ppm, driven by high levels of polycyclic aromatic
hydrocarbons (PAHs) and, to a lesser extent, the levels of dibenzofuran
and biphenyl.\121\ These compounds are largely nonexistent in clean
wood and biomass, and the contaminants are therefore not comparable in
this instance. In fact, they are present at orders of magnitude higher
than found in clean wood and biomass.
---------------------------------------------------------------------------

    \121\ We note that for several SVOCs--cresols,
hexachlorobenzene, and 2,4-dinitrotoluene, which were expected to be
in creosote, and for which information was specifically requested in
the February 7, 2013 NHSM final rule (78 FR 9111), the data
demonstrate that they were not detectable, or were present at levels
so low to be considered comparable.
---------------------------------------------------------------------------

    In the second scenario, a combustion unit is designed to burn
biomass and fuel oil. As previously mentioned, fluorine, and nitrogen
levels in CTRTs are present at elevated levels when compared to fuel
oil. However, the highest levels of fluorine (100 ppm) and nitrogen
(14,400 ppm) are comparable to, or well within the levels of these
contaminants in biomass. Likewise, SVOCs are present in CTRTs (up to
22,883 ppm) at levels well within the range observed in fuel oil (up to
54,700 ppm). Accordingly, contaminant concentration levels for
fluorine, nitrogen, and SVOCs are within the ranges identified for
either biomass or fuel oil. Therefore, CTRTs have comparable
contaminant levels to other fuels combusted in units designed to burn
both biomass and fuel oil, and as such, meet this criterion if used in
facilities that are designed to burn both biomass and fuel oil.\122\
---------------------------------------------------------------------------

    \122\ As discussed previously, the March 21, 2011 NHSM final
rule (76 FR 15456), noting the presence of hexachlorobenzene and
dinitrotoluene, suggested that creosote-treated lumber include
contaminants at levels that are not comparable to those found in
wood or coal, the fuel that creosote-treated wood would replace, and
would thus be considered solid wastes. This final rule differs in
several respects from the conclusions in the March 2011 rule. This
final rule concludes that CTRTs are a categorical non-waste when
combusted in units designed to burn both fuel oil and biomass. The
March 2011 rule, using 1990 data on railroad cross ties, was based
on contaminant comparisons to coal and biomass and not fuel oil. As
discussed above, when compared to fuel oil, total SVOC contaminant
concentrations (which would include dinitrotoluene and
hexachlorobenzene) in CTRTs would be less that those found in fuel
oil, and in fact, the 2012 data referenced in this final rule showed
non-detects for those two contaminants.

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

    As stated in the preamble to the February 7, 2013, NHSM final rule,
combustors may burn NHSMs as a product fuel if they compare
appropriately to any traditional fuel the unit can or does burn. (78 FR
9149) Combustion units are often designed to burn multiple traditional
fuels, and some units can and do rely on different fuel types at
different times based on availability of fuel supplies, market
conditions, power demands, and other factors. Under these
circumstances, it is arbitrary to restrict the combustion for energy
recovery of NHSMs based on contaminant comparison to only one
traditional fuel if the unit could burn a second traditional fuel
chosen due to such changes in fuel supplies, market conditions, power
demands or other factors. If a unit can burn both a solid and liquid
fuel, then comparison to either fuel would be appropriate.
    In order to make comparisons to multiple traditional fuels, units
must be designed to burn those fuels. If a facility compares
contaminants in an NHSM to a traditional fuel a unit is not designed to
burn, and that material is highly contaminated, a facility would then
be able to burn excessive levels of waste components in the NHSM as a
means of discard. Such NHSMs would be considered wastes regardless of
any fuel value. (78 FR 9149) \123\ Accordingly, the ability to burn a
fuel in a combustion unit does have a basic set of requirements, the
most basic of which is the ability to feed the material into the
combustion unit. The unit should also be able to ensure the material is
well-mixed and maintain temperatures within unit specifications.
---------------------------------------------------------------------------

    \123\ 78 FR 9149 states ``If a NHSM does not contain
contaminants at levels comparable to or lower than those found in
any [emphasis added] traditional fuel that a combustion unit could
burn, then it follows that discard could be occurring if the NHSM
were combusted. Whether contaminants in these cases would be
destroyed or discarded through releases to the air, they could not
be considered a normal part of a legitimate fuel and the NHSM would
be considered a solid waste when used as a fuel in that combustion
unit.''
---------------------------------------------------------------------------

    Available information regarding use of fuel oil. As discussed in
section V.C.2. of this preamble, industry stated during the comment
period that there are combustion units designed to burn biomass and
fuel oil, but did not identify specific units. A March 2013 letter from
AF&PA \124\ stated that the overwhelming majority of CTRTs burned at
paper mills are burned in boilers that are fully capable and permitted
to burn at maximum capacity rating. Most of these boilers (80 percent)
can or do burn oil during operating conditions outside of startup and
shutdown periods.\125\ Industry also stated that units operated by end-
use combustors that utilize CTRTs as an alternative fuel typically burn
a variety of ``traditional fuels,'' such as coal, biomass (i.e., hog
fuel, bark fuel, and other biomass fuel materials), and fuel oil, as
well as other materials. They stated that all of the units that burn
CTRTs also burn significant quantities of biomass given the similarity
of the fuels' characteristics. In addition, most of these units are
permitted to burn fuel oil either during start-up or during normal
operations. The EPA finds, based on this information, units do combust
multiple fuel including fuel oil and CTRTs.\126\
---------------------------------------------------------------------------

    \124\ American Forest and Paper Association and American Wood
Council's letter to George Faison, EPA. March 7, 2013. EPA-HQ-RCRA-
2013-0110-003.
    \125\ American Forest and Paper Association and American Wood
Council's letter to George Faison, EPA. March 7, 2013. EPA-HQ_RCRA-
2013-0110-003.
    \126\ The Agency notes that in 2008, information was collected
from owners and operators of combustion units across a wide variety
of industries, including use of fuel oil, in its development of
emissions standards for boilers and process heaters under section
112 of the Clean Air Act. In that context, based on the information
submitted by industry at the time (including petitioners and
others), EPA concluded that units that combust solid fuels generally
used fuel oil or natural gas only as a startup fuel and that
changing the fuel type in such units would generally require
extensive changes to the fuel handling and feeding system, as well
as modification to the burners and combustion chambers. 75 FR 32006,
32017. The information submitted for the ICR, however, also stated
that some biomass units may combust fuel oil at other times, for
example, for transient flame stability purposes if they are
combusting biomass with a high moisture content. The ICR did not
state the amount of fuel oil being combusted, or whether fuel oil
was combusted alone or in conjunction with solid fuel, such as
biomass. Although recent information outlined above shows that units
do combust multiple fuels including CTRTs and fuel oil, at the time
of the development of the boiler MACT, EPA did not have information,
including information submitted in response to the ICR, indicating
there are units designed to burn solid fuel which commonly switch
between combusting biomass and fuel oil or otherwise combusted fuel
oil as part of normal operation.
---------------------------------------------------------------------------

    Contaminant Comparisons to Coal. Data received from industry'
included information that boilers combusting CTRTs may also combust
coal, which is a traditional fuel. For purposes of contaminant
comparison to that traditional fuel, the EPA considered two scenarios.
    In the first scenario, where CTRTs were combusted in units designed
to burn only coal and biomass, contaminant levels in CTRTs were
compared to those two traditional fuels.\127\ In this scenario, as
shown in Table 4 of this preamble, maximum levels of SVOCs in CTRTs
(22,883 ppm) exceeded those in coal (2,343 ppm) and biomass (SVOC
levels largely non-existent). Thus, units that are designed to burn
only coal and biomass would not meet the legitimacy criterion for
contaminant comparison to CTRTs, an indication that discard may be
occurring.
---------------------------------------------------------------------------

    \127\ Contaminant levels in coal presented in ``Contaminant
Concentrations in Traditional Fuels: Tables for Comparison''
document available at http://www.epa.gov/epawaste/nonhaz/define/pdfs/nhsm_cont_tf.pdf. Contaminant data drawn from various
literature sources and from data submitted to USEPA, Office of Air
Quality Planning and Standards (OAQPS).
---------------------------------------------------------------------------

    In the second scenario, a combustion unit is designed to burn coal,
biomass and fuel oil. As shown in Table 4 of this preamble, SVOCs are
present in CTRTs (up to 22,883 ppm) at levels well exceeding those in
coal and biomass but within the range observed in fuel oil (up to
54,700 ppm). Fluorine, and nitrogen levels in CTRTs are present at
elevated levels when compared to fuel oil. However, the highest levels
of fluorine (100 ppm) and nitrogen (14,400 ppm) are comparable to, or
well within the levels of these contaminants in biomass. All other
contaminants in CTRTs are comparable to those in coal.
    Thus, CTRTs can be combusted in units burning coal (or other
traditional fuels), but only if the unit is also designed to burn fuel
oil and biomass. CTRTs have comparable contaminant levels in units
designed to burn biomass fuel oil and coal, and as such, meet this
criterion if used in facilities that are designed to burn those
traditional fuels. (see also section V.C.6. Response to Comments
regarding combustion of coal in units that switched from fuel oil to
natural gas).

                                              Table 4--Contaminant Ranges in Biomass, Fuel Oil, Coal & CTRT
                                                                 [In parts per million]
--------------------------------------------------------------------------------------------------------------------------------------------------------
          Contaminant                     Biomass \a\                   Fuel oil \a\                    CTRT \b\                        Coal
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                     Metal Elements
--------------------------------------------------------------------------------------------------------------------------------------------------------
Antimony (Sb)..................  ND-26........................  ND-15.7.....................  ND..........................  0.5--10
Arsenic (As)...................  ND-298.......................  ND-13.......................  ND-3.2 ND...................  0.5-174
Beryllium (Be).................  ND-10........................  ND-19.......................  ND-0.3......................  0.1-206
Cadmium (Cd)...................  ND-17........................  ND-1.4......................  ND-0.3......................  0.1-19
Chromium (Cr)..................  ND-340.......................  ND-37.......................  ND-15.3.....................  0.5-168
Cobalt (Co)....................  ND-213.......................  ND-8.5......................  ND..........................  0.5-30
Lead (Pb)......................  ND-340.......................  ND-56.8.....................  ND-9.6......................  2-148
Manganese (Mn).................  ND-15,800....................  ND-3,200....................  63--185.....................  5-512
Mercury (Hg)...................  ND-1.1.......................  ND-0.2......................  0.02-0.05...................  0.02-31
Nickel (Ni)....................  ND-540.......................  ND-270......................  ND-38.......................  0.5-730
Selenium (Se)..................  ND-9.........................  ND-4........................  ND-1........................  0.2-743
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                   Non-Metal Elements
--------------------------------------------------------------------------------------------------------------------------------------------------------
Chlorine (Cl)..................  ND-5,400.....................  ND-1,260....................  22-400......................  ND-9,080
Fluorine (F)...................  ND-300.......................  ND-14.......................  100.........................  ND-178
Nitrogen (N)...................  200-39,500...................  42-8,950....................  1,600-14,400................  13,600-54,000
Sulfur (S).....................  ND-8,700.....................  ND-57,000...................  681-3,277...................  740-61,300
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                Volatile Organic Compound (VOC) Hazardous Air Pollutants
--------------------------------------------------------------------------------------------------------------------------------------------------------
Benzene........................  .............................  ND-75.......................  ND..........................  ND-38
Phenol.........................  .............................  ND-7,700....................  ND
Styrene........................  .............................  ND-320......................  ND..........................  1.0-26
Toluene........................  .............................  ND-380......................  ND..........................  8.6-56
Xylenes........................  .............................  ND-3,100....................  0.325.......................  4.0-28
Cumene.........................  .............................  6,000-8,600.................  ND
Ethyl benzene..................  .............................  22-1,270....................  0.058.......................  0.7-5.4
Formaldehyde...................  1.6-27.......................  ............................  ND
Hexane.........................  .............................  50-10,000...................  ND
15 Additional VOC..............  .............................  ............................  ND
                                ------------------------------------------------------------------------------------------------------------------------
    Total VOC \c\..............  1.6-27.......................  6,072-19,810................  0.383.......................  14.3-125.4
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                              Semivolatile Organic Compound (VOC) Hazardous Air Pollutants
--------------------------------------------------------------------------------------------------------------------------------------------------------
Biphenyl.......................  .............................  1,000-1,200.................  137-330
16-PAH \d\.....................  .............................  3,900-54,700................  6641-21,053.................  6-253
Dibenzofuran...................  .............................  ............................  570-1,500
Quinoline......................  .............................  ............................  40.2
Cresols........................  .............................  ............................  1.51
Hexachlorobenzene..............  .............................  ND..........................  ND
2,4-dinitrotoluene.............  .............................  ND..........................  ND
Lindane........................  .............................  ............................  0.238
11 Additional SVOC.............  .............................  ............................  ND
PAH (52 extractable)...........  .............................  ............................  ............................  14-2,090
                                                               -----------------------------------------------------------------------------------------
    Total SVOC \c\.............  .............................  4,900-54,700................  7,618-22,883................  20-2,343
--------------------------------------------------------------------------------------------------------------------------------------------------------
\a\ ``Contaminant Concentrations in Traditional Fuels: Tables for Comparison'' document available at http://www.epa.gov/epawaste/nonhaz/define/pdfs/nhsm_cont_tf.pdf. Contaminant data drawn from various literature sources and from data submitted to USEPA, Office of Air Quality Planning and
  Standards (OAQPS).
\b\ (1) MA Energy Resources, LLC. February 2013 Crosstie Derived Fuel Petition; (2) URS, Evaluation of Used Railroad Ties Treated with Creosote.
  Prepared for Association of American Railroads. January 28, 2013; (3) AF&PA, Comparison of Contaminant Concentrations in Crosstie Derived Fuel with
  Traditional Fuels. February 28, 2013.
\c\ Total VOC and SVOC ranges do not represent a simple sum of the minimum and maximum values for each contaminant. This is because minimum and maximum
  concentrations for individual VOCs and SVOCs do not always come from the same sample.
\d\ 16-PAH includes: Acenaphthene, acenaphthylene, anthracene, benz(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(g,h,i)perylene,
  benzo(k)fluoranthene, chrysene, dibenz(a,h)anthracene, fluoranthene, fluorene, indeno(1,2,3-cd)pyrene, naphthalene, phenanthrene, and pyrene. 16-PAH
  is designated as Total PAH in the Table for Comparison cited in note ``a'' above.

    Contaminant Information related to dibenzofurans and dioxins. As
discussed above, the Agency requested data on dibenzofuran and dioxins,
in large part because dibenzofuran is known to be present in CTRTs and
listed as a HAP under CAA section 112 and dioxins are a pollutant under
CAA sections 112 and 129.
    Industry submitted an explanatory document in response to the
Agency's request.\128\ The document provided additional information
regarding (a) the presence of dibenzofuran in creosote and creosote-
treated wood, and (b)

whether the presence of dibenzofuran is associated with the concurrent
presence of the polychlorinated versions of these compounds, viz.,
polychlorinated dibenzo p-dioxins and dibenzofurans (PCDD/F--often
collectively termed dioxins).
---------------------------------------------------------------------------

    \128\ American Forest and Paper Association and American Wood
Council--Letter to George Faison, EPA March 7, 2013. EPA-HQ-RCRA-
0110-003.
---------------------------------------------------------------------------

    The industry' data confirms the presence of dibenzofurans. Industry
acknowledged that coal tar creosote used in preparing railroad ties may
have levels of dibenzofuran up to 4.5 percent or 45,000 ppm, and
dibenzofuran concentrations measured in seven samples of railroad ties
previously treated with creosote ranged from 570 to 1,500 ppm. However,
as stated by the industry, this compound should not be confused with
dioxins or furans, which refers to a larger group of polychlorinated
dibenzofurans and dibenzodioxins.
    The Agency agrees with the petitioner's explanation that
dibenzofuran present in the CTRTs will not result in the formation of
dioxins, but as a HAP itself, dibenzofuran is still appropriate to
include in the list of SVOCs for comparison to traditional fuels.\129\
Regarding dioxins, the document shows that dioxins will not be present
in the material. The Agency agrees that the level of chlorine during
creosote production is not sufficient to form dioxins in coal tar
creosote and therefore dioxin will not be present in CTRTs prior to
combustion.
---------------------------------------------------------------------------

    \129\ When making contaminant comparisons for purposes of
meeting the legitimacy criterion, it would be appropriate in this
circumstance to find that grouping of contaminants would not result
in discard. For example, under the grouping concept, individual SVOC
levels may be elevated above that of the traditional fuel, but the
contaminant legitimacy criterion will be met as long as total SVOCs
is comparable to or less than that of the traditional fuel. Such an
approach is standard practice employed by the Agency in developing
regulations and is consistent with monitoring standards under CAA
sections 112 and 129. See 78 FR 9146, February 7, 2013, for further
findings that relate to the issue of grouping contaminants for
purposes of determining discard.
---------------------------------------------------------------------------

c. Other Relevant Factors in a Categorical Non-Waste Determination for
CTRTs
    In their request for a categorical listing of CTRTs and in
background information submitted subsequent to that request, industry
argued that, in the context of a specific non-waste determination under
40 CFR 241.4(a), the Agency can balance the legitimacy criteria against
other relevant factors in any decision to list an NHSM categorically.
See 40 CFR 241.4(b)(5). Specifically, industry argued that the phrase
``designed to burn'' can be another relevant factor that the Agency can
consider in making a decision on listing CTRTs categorically as a non-
waste fuel. They argued that by conducting such balancing, the Agency
could allow CTRTs to be burned as a non-waste fuel in any combustion
unit that can combust biomass, whether or not the combustion unit is
designed to burn fuel oil. Thus, industry requested that the Agency re-
define or ignore the ``design to burn'' concept, as currently
interpreted for the purposes of this categorical listing.
    In arguing that the Agency can re-define or ignore the ``design to
burn'' concept, industry identified additional relevant factors to be
considered in a categorical listing for CTRTs. Specifically:
     CTRTs are functionally the same as other comparable
traditional fuels, such as fossil fuels used in a fuel mix to maintain
an appropriate Btu level for the biomass boilers, combusted in the same
units and subject to the same air pollution controls.130 131
---------------------------------------------------------------------------

    \130\ Petitioner arguments regarding functional equivalence and
use of CTRTs as a commodity are also outlined in Legal Analysis
Supporting Listing Railroad Tie Fuel as a Nonwaste under 40 CFR
241.4(a)(January 15, 2014.) American Forest and Paper Association.
Docket number EPA-HQ-RCRA-201-0110-0008.
    \131\ To further support a finding of functional equivalency,
petitioners submitted data claiming that stack emissions of PAHs
(PAHs are higher in railroad ties than in coal or biomass), are
controlled in the same way as all organic constituents present in
the other fuels used by the boilers that combust railroad tie fuel.
The Air Emissions Impact of Burning Railroad Tie-Derived Fuel.
NCASI, January 2014.
---------------------------------------------------------------------------

     CTRTs are integral to the production process similar to
any other fuel used and consistently have lower moisture content and
higher Btu value than other biomass fuel.
     CTRTs are commodity fuels--users pay $20-$30 per ton thus
industry believe that the material is not being discarded.
     High levels of PAHs in CTRTs and removal of oil delivery
mechanisms from units designed to combust fuel oil and CTRTs is not an
indication that the material is being ``discarded'' and is thus a solid
waste.\132\ As discussed previously, units will be switching from fuel
oil to natural gas. Such units designed to combust both fuel oil and
CTRTs include stoker, bubbling bed and fluidized bed boilers. Boilers
that have burned fuel oil currently or in the past will discontinue
using fuel oil, however, industry argues that they have clearly
demonstrated the ability to burn that material as a product fuel.
---------------------------------------------------------------------------

    \132\ Petitioners also argued in their December 19, 2013
background material that high PAH levels in fuels are not related to
PAH emission levels. They state that Boiler MACT carbon monoxide
(CO) limits ensure good combustion practices by minimizing PAHs and
other products of incomplete combustion (under the Boiler MACT
standards, CO is a surrogate for organic HAPs such as PAHs). Dry
fuels such as CTRTs increase heat value of the fuel mix improving
combustion temperature and conditions.
---------------------------------------------------------------------------

    In general, industry argues that any combustor that purchases CTRTs
for use as a fuel is purchasing the material because of its fuel value
and that any burning is clearly for generating energy, as opposed to
discarding CTRTs. Otherwise, they argue it would lead to the absurd
result that for a boiler that can burn fuel oil and CTRTs, the CTRTs
would be considered a non-waste fuel, whereas another boiler that
cannot burn fuel oil, but also burns CTRTs, the CTRTs would be
considered a solid waste. Some recyclers and combustors, according to
industry, have been managing CTRTs as non-waste fuel, irrespective of
the type of boiler or combustion unit.
    While we agree with industry that the agency may list an NHSM
categorically by balancing the legitimacy criteria against other
relevant factors (40 CFR 241.4(b)(5)(ii)), we do not agree that the
Agency can simply ignore any of the legitimacy criteria, particularly
the contaminant legitimacy criterion. In particular, industry argues
that any biomass material regardless of the contaminant or how
contaminated it is, should be considered a non-waste fuel.
    Purchase of the material as a commodity for its fuel value is a
factor, but not determinative when considering whether discard has
occurred. Further, elevated levels of contaminants remaining in the
material can indicate that the material is being discarded. While the
Agency recognizes that other relevant factors may be considered when
one of the legitimacy criteria are not met, there is a limit to the
levels of contamination allowed in balancing other relevant factors
with the legitimacy criteria to determine whether discard occurs.
    We do not agree with petitioner's claim that CTRTs are functionally
the same as other comparable traditional fuels, such as fossil fuels
that are used in a fuel mix to maintain an appropriate Btu level for
the biomass boilers and are combusted in the same units and subject to
the same air pollution controls. CTRT contains contaminants at levels
that are not comparable to the contaminant levels in biomass, the
traditional fuel the units' combusting CTRT are designed to burn. As
discussed, there is a limit to the levels of such contamination allowed
in balancing other relevant factors, and elevated levels of
contaminants remaining in the material can show that the material is
being discarded. Further, all CTRTs are not functionally the same as
comparable

traditional fuels since it must be processed by reclamation companies
to remove metals (spikes, nails etc.) and shredded into chips to make
it suitable as a fuel source.
    We also do not agree that CTRTs are integral to the production
process. In a previous categorical determination for resinated wood,
the Agency did conclude that the material was integrated into the
production process and was thus a categorical non-waste (78 FR 9155,
February 7, 2013). The Agency based that conclusion on information
indicating that resinated wood production facilities were specifically
designed to utilize that material for their fuel value, and the plants
could not operate as designed without the use of resinated wood.
Similar information was not received for CTRTs.
    We do agree with industry to a certain extent that removal of oil
delivery mechanisms from units designed to combust fuel oil and CTRTs
does not support a conclusive decision that the CTRTs are now being
``discarded.'' While contamination levels may be higher when compared
to natural gas, these particular facilities have demonstrated the
ability to combust fuel oil along with CTRTs and should not be
penalized for switching to a cleaner fuel. As discussed in section
V.C.3. of this preamble, the information from industry stated that
while stoker, bubbling bed or fluidized bed boilers at major source
\133\ paper mills are currently designed to combust both fuel oil and
CTRTs, few, if any, of these units may be combusting both fuel oil and
biomass in the future since those units will be switching from fuel oil
to natural gas for start-up periods and operations. The industry stated
that continued use of fuel oil during operation would result in higher
compliance costs and higher costs per Btu. Industry stated that the
switch to natural gas for operation requires replacement of start-up
fuel systems, and that the most efficient and least emitting start-up
systems use specialized burners for gas.
---------------------------------------------------------------------------

    \133\ Section 112(a)(1) of the CAA defines the term ``major
source'' to mean any stationary source or group of stationary
sources located within a contiguous area that emit or have the
potential to emit in the aggregate, 10 tons per year or more of any
hazardous air pollutant or 25 tons per year or more of any
combination of hazardous air pollutants.
---------------------------------------------------------------------------

    The proposed rule, as noted above, outlined the additional approach
the Agency considered that would include as a categorical non-waste,
CTRTs that are combusted in existing units at major source pulp and
paper mills that have been modified in order to use clean fuel such as
natural gas, instead of fuel oil. The additional approach required that
such CTRTs only be combusted if certain conditions were met (in
addition to the requirement that the CTRTs had been processed) that
were intended to ensure that the CTRTs are not being discarded. Those
conditions included in the proposal are: The CTRTs must be combusted in
an existing stoker, bubbling bed or fluidized bed boiler; the CTRTs can
comprise no more than 40 percent of the fuel used on a monthly basis;
the boiler that burned the CTRTs must have been designed to burn both
fuel oil and biomass; and the boiler is modifying its design to burn
natural gas.
    The Agency stated that the approach was meant to address only the
circumstance where fuel oil and biomass facilities were modified in
order to combust natural gas as a fuel for normal operations. The
facilities in this case would have been met the legitimacy criteria if
they did not switch to the cleaner natural gas fuel. The EPA now adopts
as a final determination the reasoning in the proposal that it is
appropriate for the Agency to decide that the switching to the cleaner
natural gas \134\ would not render the CTRT a waste fuel. The
facilities have demonstrated the ability to burn fuel oil and biomass
and should not be penalized for switching to a cleaner fuel. The CTRTs
do not become wastes solely because of the switch to natural gas.
Information indicating that CTRTs are an important part of the fuel mix
for these units due to the consistently lower moisture content and
higher Btu value as well as the benefits of drier more consistent fuel
to combustion units with significant swings in steam demand further
show that discard is not occurring.
---------------------------------------------------------------------------

    \134\ The Agency recognizes natural gas as a source of clean
energy. The burning of natural gas produces nitrogen oxides and
carbon dioxide, but in lower quantities than burning coal or oil.
Methane, a primary component of natural gas and a greenhouse gas,
can also be emitted into the air when natural gas is not burned
completely. Similarly, methane can be emitted as the result of leaks
and losses during transportation. Emissions of sulfur dioxide and
mercury compounds from burning natural gas are negligible. (See
http://www.epa.gov/cleanenergy/energy-and-you/affect/natural-gas.html.)
---------------------------------------------------------------------------

    As noted above, the Agency is adopting the additional approach with
some revisions. Specifically, based on comments received and
information in the rulemaking record, the Agency has sufficient
information to list as categorical non-wastes CTRTs that are processed
and combusted in units at major pulp and paper mills or units at power
production facilities subject to 40 CFR 63 Subpart DDDDD (Boiler MACT)
that combust CTRT and had been designed to burn biomass and fuel oil,
but are modified (e.g., oil delivery mechanisms are removed) in order
to use natural gas instead of fuel oil as part of normal operations and
not solely as part of start-up or shut-down operations. The CTRT may
continue to be combusted as a product fuel only if certain conditions
are met, which are intended to ensure that the CTRTs are not being
discarded:
     CTRTs must be combusted in existing (i.e., commenced
construction prior to April 14, 2014) stoker, bubbling bed, fluidized
bed or hybrid suspension grate boilers; and
     CTRTs can comprise no more than 40 percent of the fuel
that is used on an annual heat input basis.
    The standard is applicable to existing CTRT units burning CTRTs
that had been designed to burn fuel oil and biomass and have been
modified to burn natural gas. The standard will also apply if an
existing CTRT unit designed to burn fuel oil and biomass is modified at
some point in the future.
    The additional approach adopted for the final rule addresses only
the circumstance where contaminants in CTRTs are comparable to or less
than the traditional fuels the unit was originally designed to burn
(both fuel oil and biomass) but that design was modified in order to
combust natural gas. The approach is not a general means to circumvent
the contaminant legitimacy criterion by allowing combustion of any NHSM
with elevated contaminant levels, i.e., levels not comparable to the
traditional fuel the unit is currently designed to burn. The particular
facilities in this case had used CTRTs and would clearly be in
compliance with the legitimacy criteria if they did not switch to the
cleaner natural gas fuel. EPA determined that it is appropriate to
balance other relevant factors in this categorical non-waste
determination and that it is appropriate for the Agency to decide that
the switching to the cleaner natural gas would not render the CTRTs a
waste fuel in view of historical usage as a product fuel in stoker,
bubbling bed, fluidized bed and hybrid suspension grate boilers.
    Based on comments received on the proposed rule, several revisions
were made in the additional approach for the final rule under section
241.7(a): (1) CTRTs combusted in units at power producers subject to 40
CFR part 63 Subpart DDDDD (Boiler MACT) were added to the categorical
listing; (2) the 40% fuel load limit was changed to an annual heat
input basis; regulatory

language was added stating that units combusting fuel oil and natural
gas as well as units that had switched from fuel oil to natural gas
must combust these materials as part of normal operations and not
solely for start-up or shut-down operations; and (4) hybrid suspension
grate boilers are added to the list of acceptable boilers and to
provide further clarity regarding CTRTs combusted in ``existing''
stoker, bubbling bed fluidized bed or hybrid suspension grate boilers,
existing is defined as April 14, 2014, the date of issuance of the
proposed rule.
    See section V.C.6. Response to Comments for a further discussion of
the changes identified above. The Agency has also determined that
recordkeeping requirements under the Boiler MACT 40 CFR part 63 at
section 63.7555(d)(2) are sufficient to document compliance with these
standards. See section V.C.6. for a further discussion of recordkeeping
requirements.
5. Summary of Comments Requested
    The proposed rule identified several issues pertaining to the
listing of CTRTs as categorical non-wastes and requested comment on
those issues which are summarized below (see also section V.C.6 of this
preamble):
    Use of Multiple Fuels. The Agency requested comments specifically
on the use of multiple fuels for contaminant comparison in evaluating
whether to categorically list CTRTs, including whether fuel oil itself
should be one of the traditional fuels used for comparison given, and
any additional data that should be considered in making the
comparability determination.
    Additional Approach. Regarding the additional approach under
consideration, the Agency requested comment on the approach and the
following conditions: whether the approach should be applied to sources
at other industries in addition to pulp and paper mills (e.g.,
utilities and co-generation plants); the appropriateness of the 40
percent limit as a percentage of fuel used including the monthly or
yearly basis for the limit; if the additional approach is applied to
other industries, such as utilities, what percentage (if any) would be
appropriate for that industry(s); and whether the approach should be
subject to recordkeeping requirements.
6. Responses to Comments
a. Specific Requests for Comment
i. Use of Multiple Fuels
    Comment: Regarding the use of multiple fuels for contaminant
comparison in evaluating whether to categorically list CTRTs,
combustion units are often designed to burn multiple traditional fuels,
some relying on different fuel types at different times based on
availability of fuel supplies, market conditions, power demands, and
other factors. It would be arbitrary to restrict NHSM combustion for
energy recovery, based on contaminant comparison to only one
traditional fuel, if that unit could burn a second traditional fuel.
    Response: As stated in the preamble to the February 7, 2013, NHSM
final rule, combustors may burn NHSMs as a product fuel if they compare
appropriately to any traditional fuel the unit can or does burn. (78 FR
9149) Combustion units are often designed to burn multiple traditional
fuels, and some units can and do rely on different fuel types at
different times based on availability of fuel supplies, market
conditions, power demands, and other factors. Under these
circumstances, it would be arbitrary to restrict the combustion for
energy recovery of NHSMs based on contaminant comparison to only one
traditional fuel if the unit could burn a second traditional fuel
chosen due to such changes in fuel supplies, market conditions, power
demands or other factors. The Agency agrees with the commenter and is
retaining the regulatory standard that CTRTs are categorical non-wastes
when combusted in units designed to burn both fuel oil and biomass.
ii. Additional Approach
    Comment: As the EPA stated regarding the additional approach under
consideration, fuel switching from oil to natural gas is not evidence
of any motivation to discard CTRTs and should not affect the
classification of CTRTs as non-solid waste for combustion purposes. The
modification has nothing to do with the properties of CTRTs or the
burning of CTRTs for energy recovery, but is due to unrelated market
conditions for fuel oil and natural gas. The listing should not be
limited to only units ``that are currently designed to burn both
biomass and fuel oil but are changing (i.e., removing oil delivery
equipment) in order to burn natural gas.'' There is no rational basis
for this limitation on unit type and it is unclear why the EPA limits
this proposed ``expansion.''
    The EPA should also include units that have already switched from
fuel oil to natural gas or are currently being modified to switch from
fuel oil to natural gas, in addition to those that will switch from
fuel oil to natural gas in the future. Many pulp and paper mills
formerly combusted fuel oil, but have already moved or are moving away
from fuel oil to natural gas. The EPA's rationale applies equally in
each case.
    Moreover, if the EPA retains the limitation on the types of boilers
at pulp and paper mills that can combust CTRTs under the expanded
listing, hybrid suspension grate boilers should be added to that list
because they are similar to the listed boilers and combust CTRTs, as
well as other biomass fuels.
    Response: The Agency has determined that the additional approach
must be limited to units that are currently designed to burn both
biomass and fuel oil but are modified (e.g., removed oil delivery
mechanisms) in order to burn natural gas as part of normal operations
and not solely as part of start-up or shut-down operations. As
discussed above, the particular facilities in this case have used CTRTs
and would clearly be in compliance with the legitimacy criteria if they
did not switch to the cleaner natural gas fuel. It is appropriate to
balance other relevant factors in this categorical non-waste
determination and it is appropriate for the Agency to decide that the
switching to the cleaner natural gas would not render the CTRTs a waste
fuel in view of the historical usage as a product fuel in the stoker,
bubbling bed, and fluidized bed boilers. The nature of the CTRTs as a
product fuel does not make it a waste on switching to the cleaner
natural gas for the boiler.
    Thus, combustion of CTRTs in boiler units in the sectors identified
above that are designed to burn both biomass and fuel oil but have been
modified to burn biomass and natural gas should not be considered
discard. The additional approach is meant to address only the
circumstance where contaminants in CTRTs are comparable to or less than
the traditional fuels the unit was designed to burn (both fuel oil and
biomass) but that design has been modified in order to combust natural
gas. The approach is not a general means to circumvent the contaminant
legitimacy criterion by allowing combustion of any NHSM with elevated
contaminant levels, i.e., levels not comparable to the traditional fuel
the unit is currently designed to burn.
    Based on information from industry that in addition to stoker,
bubbling bed and fluidized bed boilers, hybrid suspension grate (HSG)
boilers also combust CTRT,\135\ the Agency is extending the additional
approach to CTRT combusted in HSG boilers. The

Agency notes, however, that use of that boiler type for combustion of
CTRT as the primary fuel may be limited. Review of HSG boilers in the
Boiler MACT Database (ICR No. 2286.01) (Version 4), indicates that all
of the boilers in the HSG subcategory fire bagasse fuels as the primary
fuel, and none report routine firing of other types of biomass fuels or
CTRTs. When the EPA finalized the HSG subcategory (76 FR 15634, March
21, 2011) the rationale for adding the subcategory was that for
combustion-related pollutants (used as a surrogate for organic HAP
emissions), the design differences for such hybrid suspension grate
boilers are significant, and combustion conditions in these types of
units are not similar to those in dutch ovens or true suspension
burners that combust fine, dry fuels. The rationale was provided solely
in the context of hybrid suspension/grate boilers designed to combust
very wet biomass fuels such as bagasse. Bagasse fuels have a moisture
content ranging between 40 and over 60 percent moisture content. By
contrast, CTRTs have a moisture content of 20 percent on average.\136\
---------------------------------------------------------------------------

    \135\ See EPA-HQ-RCRA-2013-0110-0076 in the docket for this
final rule.
    \136\ http://www.rta.org/assets/docs/RTASponsoredResearch/Environmental/creosote%20tie%20evaluation%20article%20_4_.pdf.
---------------------------------------------------------------------------

    On November 5th, 2015, EPA signed a final reconsideration for the
Boiler MACT. In that action, the definition of the HSG subcategory was
modified to require demonstration of the 40 percent moisture level (as-
fired basis) using monthly fuel analysis, instead of a 40 percent
moisture level on an annual average heat input basis. The addition of
the monthly requirement will require consistently high moisture
contents of the fuels fired in HSG boilers thus limiting the use of the
drier CTRT.
    Comment: The EPA's proposed approach should not include conditions
specifying a CTRT fuel use limit of 40 percent on a monthly basis for
the clean fuel modified unit listing (i.e., CTRTs combusted in units at
major source pulp and paper mills that are being modified in order to
use clean fuel such as natural gas, instead of fuel oil). There is no
rational basis for this limitation, since a percentage cap has nothing
to do with whether or not a material is discarded, and the EPA did not
demonstrate that this limit would provide any greater environmental
protection. In addition, the EPA should not limit the clean fuel
modified unit category to units located only at major source pulp and
paper mills. There is no reason why this should be an industry-specific
provision. A number of biomass boilers in both the forest products and
biomass power industries rely on CTRT fuel, and the EPA has information
in the record showing that a variety of other industry sectors
currently combust railroad ties, including utilities and chemical
manufacturing facilities.
    Response: The Agency is adopting the conditions under the
additional approach intended to ensure that the CTRTs are not being
discarded, including the condition that CTRTs can comprise no more than
40 percent of the fuel used on an annual heat input basis. While this
commenter disagreed on the proposed 40 percent limit on use of CTRTs in
units that were once designed to burn fuel oil but do not any longer,
we note that other commenters expressed support for this approach.\137\
As discussed in footnote 114, statements from the pulp and paper
industry indicate that CTRTs generally comprise 40% of the total fuel
load. EPA also reviewed information from the Boiler MACT database as
well as similar information obtained for CISWI units, and noted that
the reported annual heat input rates for CTRTs for units that reported
firing this material did not exceed 13 percent. Considering that CTRTs
have elevated contaminants compared to biomass and natural gas,
allowing a fuel usage percentage greater than industry has typically
used previously could be indicative of discard. Therefore, the Agency
is maintaining the 40 percent usage limitation as a reasonable
condition for the categorical non-waste determination for CTRTs in
units that have been modified to burn biomass and natural gas instead
of biomass and fuel oil.
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    \137\ See docket comment EPA-HQ-RCRA-2013-0110-0082.
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    We have also determined that the annual heat input basis is the
appropriate measure for facilities to use instead of the proposed
monthly basis. Several commenters stated that facilities already
measure and keep records on an annual basis, and we have noted that the
subcategory applicability records required by the major source boiler
NESHAP are on an annual heat input basis as well. Thus this approach
maintains consistency with other recordkeeping requirements required
under other rules and practices already in place.
    This non-waste determination approach is also extended to CTRTs
combusted in units at power production facilities subject to 40 CFR
part 63 Subpart DDDDD (Boiler MACT) in addition to major source pulp
and paper mills. The information sources cited above indicate that
these types of units may combust both CTRTs and fuel oil. The sources
did not show that chemical manufacturing facilities combust both types
of fuels, thus these facilities were not included in the categorical
non-waste determination for units that have been modified to burn
biomass and natural gas instead of biomass and fuel oil.\138\
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    \138\ 40 CFR 241.2 defines power producer as a boiler unit
producing electricity for sale to the grid. The term does not
include units meeting the definition of electricity generating unit
under 40 CFR 63.10042 of the Utility Mercury and Air Toxics
Standards rule.
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    Comment: With regard to whether combustors should be required to
keep records that the conditions for burning of CTRTs described above
have been met, and the additional recordkeeping requirements to show
that the conditions in the additional approach are met, are
unnecessary. Any potential issues should already be adequately
addressed by the recordkeeping provisions already in place in
applicable Boiler MACT and NSPS requirements, state and local
regulatory requirements, and facility permits. Further, the existence
of a record does not demonstrate whether or not discard is occurring
under RCRA. The EPA should continue to rely on the record-keeping
requirements under the Clean Air Act rules.
    Other commenters supported such recordkeeping requirements,
explaining that the EPA and/or delegated state or local air agencies
will have no way to ensure compliance with the conditions without
requiring recordkeeping. If required, recordkeeping should be
streamlined with air quality requirements, in other words, one system
may support the NHSM determination and air pollution control
requirements.
    Response: The Agency has concluded that additional specific
recordkeeping requirements are not required to determine compliance
with the additional approach. Current recordkeeping requirements for
boilers under 40 CFR 63.7555 require documentation that the material is
listed as a categorical non-waste under Sec.  241.4(a) of this chapter,
which would include records demonstrating adherence to any conditions
applied to the categorical non-waste determination, such as the 40
percent annual heat input limitation.
b. Additional Comments
    Comment: The EPA should expand this additional approach to allow
the combustion of CTRTs in biomass boilers, and specifically, biomass
boilers that have already or in the future will convert from coal to
biomass. The

conversion of a unit from coal to biomass reduces the steam generation
capacity compared to the original design. A portion of a higher Btu
fuel (such as CTRTs) is incorporated into the mix to make the
conversion successful.
    It is environmentally preferable to avoid the use of coal or fuel
oil for that higher Btu fuel, and the EPA shouldn't discourage
facilities from switching to biomass by not allowing the co-firing of
CTRTs. The EPA can balance other factors against the contaminant
legitimacy criterion, and the environmental benefits of coal-to-biomass
conversion are a relevant factor to be considered.
    Many biomass boilers in the forest products industry rely on CTRT
fuel but are not current or former users of either oil or coal. CTRT is
a significant fuel for a number of biomass plants and will become
increasingly important as facilities are forced to secure feedstocks
from non-forest product sources.
    The biomass power industry operates with mostly grid-connected
standalone power plants which use organic materials in the production
of energy. These commenters reported that 20-35 percent of the organic
materials used in these facilities are CTRTs, stressing that CTRTs
enhance boiler performance and efficiency, and are therefore valuable
to these facilities because of their high BTU value, low moisture
content, and low ash.
    Biomass power facilities may also be subject to Renewable Portfolio
Standards which provide states with a mechanism to increase renewable
energy generation. Such programs require energy utilities to supply a
minimum amount of customer load from eligible renewable energy sources,
such as biomass rather than fossil fuel sources such as fuel oil.
    Response: The Agency recognizes the importance of CTRTs as a fuel
to the biomass power industry and to boilers designed specifically for
the use of biomass as a fuel. Indeed, there may be environmental
benefits to allowing CTRT use. The statutory requirement under RCRA,
however, is to determine whether the material is a waste when burned as
a fuel. The environmental and efficiency benefits, moreover, would
accrue if the facilities were burning under CAA 112 or 129. Thus, most
of the policy arguments propounded by the comment may be valid but not
necessarily relevant to whether material is discarded.
    The key for the facilities discussed in the comment is the use of
both fuel oil and biomass as fuels that the facilities are designed to
burn. Since the comment discusses facilities that do not use fuel oil
in their fuel mix now or in the past, they do not meet legitimacy
criteria for contaminant comparison and will not be eligible for the
categorical listing regarding CTRTs. Under these conditions, the CTRTs
have been discarded when they are burned as a fuel.
    Comment: The EPA's proposal included the combustion of CTRTs as a
non-waste fuel, and stressed that these materials are a valuable
commodity and a legitimate alternative fuel. However, combustion of
CTRTs should not be limited to only units ``designed to burn biomass
and fuel oil.'' Such limitations may be necessary when evaluating case-
by-case NHSMs against the legitimacy criteria, but, they are not
appropriate for the categorical listing of a non-waste fuel. For
example, in listing TDF (tire-derived fuel) as a categorical
non[hyphen]waste fuel, the EPA compared the contaminants in scrap tires
to the contaminants in coal, which was considered the traditional fuel
that TDF typically replaces, to satisfy the third legitimacy criterion.
However, it is important to note that no ``designed to burn''
conditions are included in the categorical non[hyphen]waste listing for
TDF. TDF are NHSMs that are categorically not solid waste when used as
fuel in a combustion unit. Therefore, the specification of ``designed
to burn'' conditions associated with the proposed non[hyphen]waste fuel
listing for CTRTs is inconsistent with previous rulemakings and
non[hyphen]waste fuel determinations.
    The ``designed to burn'' condition was intended to determine which
traditional fuels should be the basis of comparison for the contaminant
levels in the material under evaluation as a non[hyphen]waste fuel, not
to put limitations on the use of the NHSM as non[hyphen]waste fuel. As
the EPA stated ``the reason we analyze what a unit is designed to burn
is to decide the traditional fuel(s) to which contaminants should be
compared. This comparison is then used as an aid to decide whether the
NHSM is being legitimately used as a fuel or whether excess
contaminants show that the burning is waste treatment'' (78 FR 9149).
    Response: The Agency disagrees that designed to burn conditions or
limitations are inappropriate for categorical non-waste determinations.
Further, the commenter's argument as to why the ``designed to burn''
condition should not put limitations on the use of the NHSM as
non[hyphen]waste fuel is unclear. The purpose of the designed to burn
condition is to ensure a facility is not combusting CTRTs as a means of
discard. Discard would be occurring if the unit is not designed to burn
CTRTs with elevated levels of PAHs. As discussed in section V.C.4. of
this preamble, to meet legitimacy criteria and ensure discard is not
occurring, any categorical non-waste (as well as materials determined
to be non-waste on a case-by-case basis) must contain contaminants or
groups of contaminants at levels comparable in concentration to or
lower than those in the traditional fuel(s) which the combustion unit
is designed to burn (40 CFR 241.3(d)(1)(iii), 40 CFR 241.4(b)). If a
facility compared contaminants to a traditional fuel that the unit is
not designed to burn, and the fuel is highly contaminated, combustion
of that fuel would be considered discard.
    As further discussed in section V.C.4. of this preamble, for CTRTs,
the Agency considered traditional fuel contaminant comparison
information for biomass, fuel oil and coal. To meet the contaminant
legitimacy criterion, the Agency determined that CTRTs must be
combusted in units designed to burn biomass and fuel oil due to
elevated levels of SVOCs, or as described, above in specific industry
facilities that have switched from burning fuel oil and biomass to
natural gas and fuel oil. Units designed to burn both biomass and fuel
oil may, in addition, burn coal or other traditional fuels if the unit
is also designed to burn that material. With respect to the comment's
view of the TDF categorical listing, the EPA first notes that that
listing has not been reopened for any comment. Regardless, the EPA
disagrees with the comment that there is no designed to burn provision
in the categorical listing. Any categorical listing imposes a
requirement that legitimacy criteria must be met, as is the case for
any material burned as a fuel in order to be burned as a product fuel.
Facilities that are not designed to burn coal may not burn TDF because
they will be burning a ``dirtier'' fuel than would normally be burned
by the facility. While a separate case-by-case determination regarding
contaminants does not have to be made, TDF may not be burned in an oil
or gas-fired facility under CAA section 112. In such a case there would
be substantial burning of waste contaminants, which would result in the
application of CAA section 129 standards.
    The categorical listing for tires was based on the determination
made in the March 21, 2011 rule (76 FR 15456) that TDF had contaminants
at levels comparable to or less than coal, the traditional fuel which
TDF would replace.139 140 The Agency did not

receive information on contaminant comparisons to other traditional
fuels besides coal. It is not necessary for the EPA to repeat the
importance of the legitimacy criteria in every provision in its
regulations.
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    \139\ See 78 FR 9154.
    \140\ See 76 FR 15494.
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    Comment: Seven boilers at a facility are built and designed as
biomass boilers, and use fossil fuels for startup and flame
stabilization. However, only three of the boilers are permitted and
equipped to burn fuel oil, and the remaining units are permitted and
equipped to use natural gas. The categorical listing of CTRTs as a non-
waste fuel in units designed to burn fuel oil would only allow listing
CTRTs as a fuel for one of its facilities (three boilers), while being
a waste in the others, despite each of the units being designed to burn
primarily solid fuels such as CTRT.
    CTRTs should be allowed to be used as a fuel in units designed,
built and operated to burn biomass, provided that the units are
operated in compliance with their air permit regardless of their
capacity to burn fuel oil. These units are designed to burn solid
fuels, and CTRTs are a solid fuel. Requiring boilers to be equipped
with fuel oil delivery systems would result in unnecessary permitting
and burden with no environmental benefit. The commenter further notes
that the EPA's concerns on combustion by-products and PAH are best
addressed through air permitting.
    Response: The Agency does not agree that CTRTs should be allowed to
be used as a fuel in units designed to burn only biomass. In order to
legitimately combust CTRTs, the unit must be designed to burn both
biomass and fuel oil. As stated in section V.C.4.b.iii., of this
preamble, where a combustion unit is designed to only burn biomass, the
EPA compared contaminant levels in CTRTs to contaminant levels in
biomass. In this scenario, the total SVOC levels can reach 22,883 ppm,
driven by high levels of PAHs and, to a lesser extent, the levels of
dibenzofuran and biphenyl.\141\ These compounds are largely nonexistent
in clean wood and biomass, and the contaminants are therefore not
comparable in this instance. In fact, they are present at orders of
magnitude higher than found in clean wood and biomass. Thus, if a unit
combusts CTRTs and the unit is designed to burn only biomass, the unit
would be able to burn excessive levels of contaminants, which would be
waste components. This would constitute discard.
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    \141\ We note that for several SVOCs--cresols,
hexachlorobenzene, and 2,4-dinitrotoluene, which were expected to be
in creosote, and for which information was specifically requested in
the February 7, 2013 NHSM final rule (78 FR 9111), the data
demonstrate that they were not detectable, or were present at levels
so low to be considered comparable.
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    The Agency also disagrees that because the units are operated in
compliance with the air permits, the units should be allowed to burn
CTRTs regardless of the capacity to burn fuel oil. The determination
whether CTRTs are a waste or a non-waste and, thus, whether CTRTs can
be combusted in a particular unit is made prior to combustion of the
material. Emission standards, either CAA section 112 or CAA section
129, are applied through the permit based on the waste-non-waste
determination. The concept of the NHSM rule is to determine whether
particular materials should be burned as waste fuels or product fuels,
while the air permit emission standards help ensure protection of human
health and the environment for burning of the NHSM in the unit.
    Comment: The EPA has stated that ``information indicating that
CTRTs are an important part of the fuel mix due to the consistently
lower moisture content and higher Btu value, as well as the benefits of
drier more consistent fuel to combustion units with significant swings
in steam demand, further suggest that discard is not occurring'' (79 FR
21028). This statement supports the determination that CTRTs are
functionally equivalent to traditional fuels they replace.
    When balanced against the contaminant legitimacy criterion it
should outweigh any implication the EPA is inferring from the PAH
levels that discard is occurring. CTRTs may have higher concentrations
of such semi-volatile organic compounds in comparison to biomass, but
the EPA should give more weight to other factors demonstrating that
CTRTs are fuel rather than waste (such as the long[hyphen]standing
practice of purchasing CTRTs as a viable fuel source for boilers).
    EPA also stated in the December 2011 preamble (76 FR 80471) that
``certain NHSMs may not meet the legitimacy criteria, especially the
`contaminant legitimacy criterion,' in all instances, but the material
would still generally be considered a non-waste fuel.'' It is
appropriate to balance the legitimacy criteria and other relevant
factors in determining that a NHSM is not a solid waste when used as a
fuel in a combustion unit. The motivation of the combustor is a
significant factor that should be considered in a non-waste
determination. CTRTs are generally purchased under contracts to provide
a reliable, cost-effective fuel source, rather than burned to destroy a
group of contaminants. Use of CTRTs are important in reducing carbon
dioxide emissions, maintaining capacity for managing agricultural
biomass and urban wood, and the continued economic viability of many
facilities as relevant factors for the EPA to balance with the