WastingAwayEPA’s definition of solid waste and how it could impact alternative fuel use.

By Max Lee, Ph.D., P.E., Angela Morrison, and Carl Eldred

Over the past few decades, the U.S. cement industry has continually expanded its use of alternative fuels and raw materials. Yet, the U.S. Environmental Protection Agency’s (EPA’s) new rule defining solid waste for purpose of air regulations, “The Identification of Non-Hazardous Secondary Materials [NHSM] that are Solid Waste” (40 CFR 241), will impact the cement industry’s use of these fuels and ingredients. Kiln operators and owners must pay attention to the details of this NHSM rule or important energy resources will be needlessly wasted.

Coal and other fossil fuels have been mainstay fuel sources for cement kilns because they are readily available and typically cheap sources of energy. Substituting fossil fuels and virgin materials are the next step for the industry to improve sustainability and remain competitive. Typical alternative sources include a broad range of materials such as used tires, coal ash, plastics, biomass, agricultural residues, and engineered fuels processed from discarded material. These alternatives help diversify fuel supplies and raw materials, stabilize projected business plans, reduce greenhouse gas emissions, and conserve resources. And the financial benefits from a viable alternative fuels program can be significant where traditional fuel costs can be greater than 50 percent of operation costs. Further, the impact of reduced use of traditional fuels is not insignificant given the inherent concerns of traditional fuel production.

But the trend could come crashing down if industry is not careful. EPA issued this NHSM rule defining solid waste for purposes of the Clean Air Act (CAA) on March 21, 2011, which could severely affect whether a secondary material is a viable fuel or ingredient for a kiln given how severely different the air regulations are for burning fuels versus solid waste. If an owner/operator uses a particular alternative that is determined to be a solid waste, then the kiln becomes an incinerator and very stringent air emission regulations will apply.

In summary, if the kiln burns traditional or alternative fuels not considered to be a waste, the air emissions are regulated under the Cement National Emission Standards for Hazardous Air Pollutants (NESHAP, also called MACT (40 CFR 63 Subpart LLL)) rules, and if the kiln burns any material considered to be solid waste then the kiln is regulated under the CISWI rule as a solid waste incinerator (Commercial or Industrial Solid Waste Incinerator, 40 CFR 60 Subparts CCCC and DDDD). Rather than providing clarity, however, this new definition of solid waste raises a myriad of questions. As a result of the questions that remain and because materials determined to be solid waste will subject kilns to more stringent “incinerator” air regulations, industry is in an uproar. Over the last few months since the new NHSM rule was issued, there has been little clarification and the tangled regulatory webs continue to be woven.

This article digs into the main provisions of the NHSM rule, including the points of contention, highlights major concerns of the difference in the cement MACT standards and the incinerator standards for air emissions, and explains how industry is fighting back.

‘Alternative’ Fuels: The Growing Trend

The use of “secondary materials” (meaning any material that is not the primary product of a manufacturing or commercial process) as alternative fuels and ingredients in cement kilns is not a new concept. While the practice is growing in the United States, other countries have used secondary materials for longer periods of time and in far greater amounts with replacement of fossil fuel exceeding 80 percent in many plants in Europe.1 Indeed in many developed countries, fossil fuels are the alternative fuel for cement production. In the United States, EPA has heavily promoted kiln fuels from secondary materials2 and has stated that the use of secondary materials (i.e., NHSM) compared to traditional fuels does not appreciably affect air pollutant emissions.3

Despite EPA’s expressed desire for increased use of alternative fuels, the classification of an alternative fuel as a “solid waste” is very likely to eliminate or at least greatly diminish the alternative fuel market. Despite the EPA’s good intentions for particular alternative fuels not to be solid waste, many ambiguities of the rule can be interpreted in such a way as to re-define those fuels as waste. Industry is therefore working on a number of different fronts to get a functional rule that promotes alternative fuels.

The Impact of CISWI

CISWI air regulatory requirements for new and existing kilns, as promulgated by EPA earlier this year, are severe. Even though EPA finalized CISWI, its effective date was put on hold because EPA knew it would be controversial, and it is. Even if the CISWI requirements are revised to be less stringent, the requirements are likely to remain more stringent than the Cement NESHAP. The EPA requirements for new CISWI kilns are so severe that EPA does not expect any new CISWI units to be built.

The cement industry is already making changes to reduce emissions to comply with the new air emission standards under the Cement NESHAP. If the alternative fuel/material is considered to be a solid waste, then the Cement NESHAP would no longer apply, and the kiln would instead be subject to the CISWI rule. Due to the stringency of the CISWI regulations, nearly all kiln systems would only be able to meet the new standards with major additions of air pollution control equipment far beyond that required for compliance with the Cement NESHAP and which is prohibitively expensive.

For example, for just one of the expected controls, EPA notes that capital costs for carbon injection are $3.118 per ton of clinker, and annual costs are $0.7525 per ton of clinker. Thus, for a typical kiln producing 1 million tons of cement per year, additional capital costs of approximately $3.12 million, and additional annual costs of $752,500 would be incurred to install activated carbon injection (ACI).4 Many of the possible combinations of needed new control equipment systems have not been tested on existing cement kilns. Consequently, the claimed improvements in emissions are unproven.

Furthermore, the CISWI rule emission limits, as finalized, are not designed to address the various modes of kiln operation. For example, CISWI limits mercury to the same level regardless of operating with the raw mill up or mill down. Precalciner kiln operators know that mercury emissions vary greatly in these modes. Table 1 (below) shows just how severe the CISWI limits are compared to the active Cement NESHAP. The dioxin/furan limits alone under CISWI (0.007 ng/dscm TEQ) are jaw dropping to knowledgeable modern kiln operators.

In addition, the stigma of being labeled a “solid waste” incinerator is a public relations lightning rod that alone could stop kiln operators from using a particular material, regardless of cost and availability.

Table 1: Comparison of Emission Limits

What is this NHSM rule, and how does it define solid waste?

In 1990, when Congress overhauled the CAA, EPA was directed to establish emission standards for solid waste incineration units, defined as those units that combust “solid waste” material from commercial or industrial establishments or the general public.5 The CAA does not contain a definition of solid waste, but instead refers to the Resource Conservation and Recovery Act (RCRA) for the definition.6

When EPA first promulgated regulations establishing emission standards for CISWI units in 2000, rather than determining what constitutes solid waste, the rule sought to define CISWI units as any unit using non-hazardous solid waste that did not recover energy. This was eventually challenged on the premise that the unit could be used for energy recovery and destruction of solid waste and still not be a CISWI unit. Under pressure, EPA decided to remand its own rule following litigation and in September 2005 published a revised rule. The 2005 rule maintained the definition of a CISWI unit that was based on whether the unit was capable of energy recovery. In 2007, the D.C. Circuit Court vacated the definition of a CISWI combustion unit explaining the definition of a CISWI combustion unit should be for combustion of any solid waste, regardless of energy recovery.7 Consequently, EPA had to go back to the drawing board and define “solid waste” to identify secondary  materials that if combusted would subject the unit to CISWI.

EPA’s Approach under RCRA

EPA’s task of defining solid waste for purposes of the CAA was complicated by the expansive definition of solid waste under RCRA, which includes garbage, refuse, various sludges, and “other discarded material.” EPA had only interpreted the term “discarded material” in the context of hazardous wastes (a material must first be a solid waste before it can be regulated as a hazardous waste) because the regulation of solid waste and its reuse has been largely undertaken by the states. Unsurprisingly, for other RCRA purposes EPA had interpreted the term broadly to include any secondary material that is abandoned, recycled or is considered inherently waste-like.8 For example, secondary materials are considered to be solid waste if they are abandoned by being burned or incinerated.9

More troublesome, however, is that a secondary material is classified as solid waste under RCRA if it is recycled by being burned for energy recovery or used to produce a fuel.10 EPA has developed some exemptions from this classification for materials that are recycled in a specific manner.11 However, this regulatory construct places the burden on the recycler to establish that the recycling activity satisfies the exemption and that the secondary material is not a solid waste. Understandably, this has proven very contentious and has resulted in a number of cases being filed over the years challenging EPA’s classification of a recycled material as a solid waste.12

Rather than simplifying matters by taking a new approach in the NHSM rule, EPA stayed with what was familiar and established limited exemptions from the definition of solid waste for NHSM that are used as a fuel or as an ingredient in a combustion unit.13

The NHSM rule provides four options for determining whether a NHSM is a fuel or a waste:

  • · Option A: A material meets the definition of “traditional fuels”;
  • · Option B: The material is not “discarded” and meets the “legitimacy” criteria;
  • · Option C: A discarded material is sufficiently processed and meets the “legitimacy” criteria; or
  • · Option D: The EPA regional administrator makes a determination following a petition process.

Who’s responsible?

The kiln owner/operator is responsible to make the determination with documentation confirming whether a NHSM is a waste.

Option A - What is a “traditional” fuel?
The NHSM rule includes a broad range of traditional fuels (e.g., coal, oil, and natural gas), with the premise that these materials are commonly used materials and not “sham” recycling (i.e., incineration to dispose of waste). Clearly, this caveat is not an issue as most alternative fuels are not considered traditional fuels, e.g., engineered fuel, tires.

Option B - What does “discarded” mean?
If a material remains within the control of the generator, it is not considered “discarded.”  Also, in response to numerous comments from the cement industry and others, the NHSM rule provides that whole tires from an established collection service are not considered “abandoned,” and therefore not “discarded.” Tires from a landfill, however, would be considered “discarded” under the rule, and those tires would need to meet the requirements of Option C to avoid being regulated under CISWI. Similarly “resinated wood” used in a combustion unit is not considered to be “discarded.” Materials that remain within the control of the generator, tires and resinated wood, however, must still meet the “legitimacy” criteria discussed below.

Option C - Can my alternative materials be defined as processed and meet the “legitimacy” criteria?
The rule provides that NHSM that is “sufficiently processed” and meets the “legitimacy” criteria will not be considered a waste. The title “legitimacy” comes from the concept that use of the NHSM is legitimate and not “sham” recycling (i.e., disposal in the process). NHSM that meets this test is considered reclaimed, resulting in a “new” product that has not been discarded, and therefore not a solid waste.

What does it mean to “sufficiently process” a material?
The first part of the option C test is whether the NHSM has been “sufficiently processed.” The rule defines processing to mean operations that “transform” a NHSM into a legitimate fuel, including but not limited to operations that remove or destroy contaminants, operations that significantly improve the fuel characteristics of the material such as sizing or drying the material in combination with other operations, and operations that chemically improve the as-fired energy content.

EPA specifically stated that “minimal” operations that result only in changing the size of the material such as through shredding would not constitute sufficient processing for purposes of this rule. For example, discarded tires (from a landfill) would not only need to be shredded, the metal would also need to be removed to be sufficiently processed. The properties of the new product created through the processing must provide the end user with assurances that the new product (i.e, the manufactured fuel, our term not EPA’s) will consistently satisfy the legitimacy criteria.

What are the “legitimacy criteria”? There are three criteria that need to be addressed to determine whether a material is legitimately being used as a fuel. The material must be managed as a valuable commodity, have significant heating value and have comparable levels of contaminants as fuels the combustion unit was designed to burn.

Managed as Valuable Commodity.  From the time a NHSM is processed to generate a fuel until the time it is combusted, it must be managed as a valuable product and stored within a reasonable time frame, i.e., it should be managed in a similar manner as traditional fuel. Similar to traditional fuel, the alternative fuel would need to be “contained” to prevent release or adverse impacts to human health and to the environment.

Significant Heating Value as a Fuel.  EPA generally considers 5,000 Btu per pound (as fired) or greater to be a meaningful heating value. EPA simply wants to avoid operations where use of a manufactured fuel is really being done as “sham” recycling. Tires, for example, easily meet this criterion.

Contaminant Comparison.  The most controversial portion of the legitimacy criteria is the contaminant comparison. The NHSM rule requires that contaminant levels in a NHSM must be “comparable in concentration to or lower than those in traditional fuels which the combustion unit is designed to burn.14

What is a contaminant for comparison purposes?
EPA defines “contaminants” to be any contaminant that results in the emission of any of the 188 hazardous air pollutants (HAPs) listed under CAA Section 112 or the nine pollutants regulated under CAA Section 129. While the CISWI rule sets air emission limits for only nine pollutants as required under the CAA, EPA (through the solid waste rule) is requiring evaluation of those nine plus 188 other pollutants. EPA should limit its contaminant comparison to only the nine CISWI pollutants. Also, the language of the rule conflicts with whether the emissions are relevant in the comparison. While it is more logical, from an air quality perspective, to consider air emissions resulting from fuel combustion, most of the rule language focuses on only comparing constituents in the fuel itself. Clearly, some of the 188 HAPs (e.g., di-isocyanates) should not be considered.

The rule nevertheless requires a “direct comparison of the contaminant levels in the NHSM to the traditional fuel itself,” in an effort to ensure there is no resultant increase in air emission levels associated with the use of NHSM as fuels. The absurdity of the disconnect in EPA’s presumption that fuel content is directly correlated to emissions is very well demonstrated for cement kiln combustion of sulfur. The sulfur in fuel used in a precalciner kiln is well absorbed in the clinker and does not well correlate to SO2 emissions, whereas the sulfites in raw materials are volatilized and result in SO2 emissions. EPA has more recently recognized that it would be impractical to identify and quantify every individual compound that may result in air emissions. EPA is expected to issue further guidance later this year.

How do I determine the traditional fuels that the combustion unit is “designed to burn”?
Another controversial issue associated with the legitimacy criteria is determining what "designed to burn" means. Based on analogous EPA terms used in CAA rules, the term under the NHSM rule should be focused on the design of the unit and not what the unit is capable of burning, permitted to burn, or currently burning. For example, though a kiln has only fired coal, the kiln manufacturer could have designed it to use all grades of oil, petroleum coke, and wood. Therefore, the owner/operator needs to first carefully review the kiln’s design and determine all types of traditional fuels that should be considered.

Unfortunately, EPA has stated in a recent letter implementing the NHSM rule that "[a] unit designed to burn coal is one that would not require extensive modifications and retrofitting to burn coal."15 This apparent interpretation is contrary to how the term has been used under the CAA where for almost four decades EPA has interpreted "design" to refer to the inherent design of a unit, not whether the existing facility is currently "capable" of accommodating a fuel. EPA has specifically differentiated between design and current facility capabilities.

Even when new fuel handling equipment, retrofits, or physical changes are needed to burn a different fuel, and even if there is a large expense associated with this work, if the original blueprints or construction specifications of the unit would have accommodated the fuel, then the unit is deemed to have been "designed" to accommodate the fuel.16 Because this new approach by EPA would be such a departure from the CAA interpretation of the same term, industry will pursue this further with EPA.

Where do you obtain contaminant data on traditional fuels?
The contaminant levels in the NHSM need to be compared to contaminant levels for all of the traditional fuels that the kiln is “designed” to burn, as explained above. And even for coal, the worst-case coal should be considered, including not only domestic sources but foreign sources as well. If your unit is designed to burn coal, then coal from anywhere in the world should be included in the comparison. There are sources of data for contaminant levels readily available, such as the USGS.  While EPA has provided some contaminant information, EPA has solicited additional information from industry. EPA has stated that direct measurement and operator knowledge can also be used.

What is “comparable to or lower than”?
The NHSM contaminant concentrations must be at levels that are “comparable to or lower than” those in traditional fuels which the combustion unit is designed to burn. EPA states that this term does not necessarily mean equivalent to but rather means the contaminants are similar “within a small acceptable range.”  The term “small acceptable range” is undefined, and EPA provided inconsistent examples of what is meant by this term. As shown in the chart below, the difference that is considered comparable varies greatly from pollutant to pollutant without explanation or clear rationale.


TABLE 2: Percent Differences of Comparable Contaminants18

Further Ambiguities
EPA is unclear on just how many samples to compare, what methods should be used for analysis, and the total number of contaminants to compare. EPA is also unclear on whether the comparison is to be made for each individual contaminant or by groups of contaminants. EPA has recently suggested it may consider statistics such as the 90th percentile of the available data (also not included in the rule or preamble). To use such statistics, then 10 percent of the traditional fuels would not be considered comparable. EPA, with industry help, is continuing to gather more data on contaminant levels. In addition, while the preamble to the final rule indicates that each individual contaminant is to be compared, EPA has indicated that it may be acceptable to group contaminants for the comparison (e.g., compare non-volatilized metals as a group). Interestingly, EPA has also stated that the comparison could be based on categories of traditional fuels, i.e., solid, liquid, and gaseous fuels, rather than individual types of fuels. Obviously, formal EPA guidance on these issues may help, but confusion and uncertainty is likely to remain.

Option D – Should I consider a petition to EPA?
For NHSM not meeting options A, B or C, EPA has established a fourth option which is an administrative process for seeking a formal determination that a NHSM used as a fuel in a combustion unit is not discarded and is not a solid waste. A facility interested in using a NHSM that would otherwise be considered a solid waste may petition the EPA Regional Administrator. States or private entities may also submit petitions on behalf of others, including for example, a whole class of users of a specific NHSM within a state. The applicant must demonstrate that the NHSM has not been discarded (meaning not abandoned, disposed of, or thrown away) even though the material might have been transferred from the original generator to a third party before being used as a fuel.

In deciding whether to grant or deny an application, EPA must consider the following five criteria:19

  1. Whether market participants treat the NHSM as a fuel rather than a waste;
  2. Whether the chemical and physical identity of the NHSM is comparable to commercial fuels;
  3. Whether the NHSM will be used within a reasonable time frame given the state of the market;
  4. Whether the constituents in the NHSM that are released to the air, water, or land (from the point of generation to the point of combustion) are at levels comparable to what would otherwise be released from traditional fuels; and
  5. Any other relevant factors.

EPA has no imposed deadline within which to make a decision on petitions that are submitted. EPA plans to maintain the authority to make these decisions, and not delegate that authority to the states. However, EPA recognizes that final decisions must be made prior to issuance of any related state air permits. EPA plans to make its decisions available to the public through an online database, which should help support national consistency and minimize redundant efforts.

Industry Opposition and Challenge
Numerous industries have formed coalitions to address their concerns with the NHSM rule in a four-pronged strategy: petitions to EPA, litigation in the courts, Congressional action, and negotiations with EPA. The list of concerned groups is in the hundreds and includes groups such as the Portland Cement Association, Construction Materials Recycling Association, the U.S. Chamber of Commerce, the National Solid Waste Management Association, and the American Chemistry Council. The main concern, as mentioned above, is the contaminant comparison.

Petitions to EPA. Numerous groups submitted petitions under the procedures of the Administrative Procedures Act for EPA to delay the effective date of the NHSM rule where “justice so requires” due to the intimate tie between CISWI and the Cement  MACT (either stayed or at least portions under reconsideration) and the ambiguities of the NHSM rule. As of the date of this article, EPA has not responded to these petitions and the industry folks are looking more towards congressional action.

Litigation in the Courts. Many of these same groups and companies sued EPA in the United States Circuit Court of Appeals for the District of Columbia challenging the NHSM rule. These suits were consolidated into one action (Waste Management Inc. v. EPA, Case 11-1148), which is still in the early stages and written briefs have not yet been filed.

Congressional Action. The U.S. House and Senate have introduced at least three bills, HR2681, HR2250 and S1392 that would address the new definition of solid waste. If enacted, these bills would essentially “trump” the NHSM and CISWI rules. As drafted, the bills direct EPA to re-propose these rules to categorically exempt NHSM from the definition of solid waste, provided they are combusted for energy recovery. In particular, HR2681 (Cement Sector Regulatory Relief Act of 2011) addresses both CISWI and the Cement NESHAP. These bills are moving slowly and it is unclear whether they will gain sufficient momentum to pass. Recent congressional committee debates show the bills may have traction given the country’s economic state.

Meeting/discussions with EPA. In an effort to work with industry to address the many concerns outlined above, EPA has begun to issue a few “comfort letters” and plans to issue formal guidance on how to conduct the contaminant comparison.20 The cement industry is working with EPA to confirm various common fuels and materials such as coal ash to be either traditional fuels/ingredients, are not discarded, or meet the processing and legitimacy criteria.

While helpful, industry is concerned these comfort letters do not provide the same compliance and regulatory assurance that formal rule revisions would. Inexplicably, EPA seems insistent upon using guidance documents rather than rule changes to address deficiencies in the rule.


Once the CISWI rule becomes effective and a compliance deadline established, cement kiln operators will need to quickly determine whether any alternative fuels or ingredients being used constitute solid waste. While EPA appreciates that guidance is needed for implementation of the NHSM rule, it is highly likely that uncertainties will remain associated with these determinations. This uncertainty stymies businesses that are unsure of what regulations apply and how to prepare for the cost of the regulations. This uncertainty ultimately leads to reduced usage of alternative fuels. These alternatives to fossil fuels and virgin materials are our nation’s treasure chest and should not be wasted away. Let’s see if EPA can untie its knotted conflict of regulations and promote sustainability through resource conservation and recovery.

Max Lee, Ph.D., P.E., is a Principal Engineer and President of Koogler & Associates, Inc., Gainesville, Fla., (+1) 352-377-5822; This email address is being protected from spambots. You need JavaScript enabled to view it..

Angela Morrison and Carl Eldred are attorneys with Hopping Green & Sams, P.A., Tallahassee, Fla., (+1) 850-222-7500; This email address is being protected from spambots. You need JavaScript enabled to view it. and This email address is being protected from spambots. You need JavaScript enabled to view it.. The authors would like to thank Matt Tribby, Karl Seltzer, and Kyle Ulmer with Koogler & Associates for their contributions.


May 2010, Table 4.16, http://eippcb.jrc.ec.europa.eu .

and Raw Materials, EPA 2008, http://www.epa.gov/sectors/pdf/cement-sector-report.pdf.

3 76 FR 28318

4 EPA-HQ-OAR-2003-0119-1970.1, Michael Benoit, Cement Kiln Recycling Coalition, Comment on Proposed CISWI Rule.

5 CAA § 129(g)(1).

6 CAA § 129 (g)(6).

7 Nat. Res. Def. Council v. EPA, 489 F.3d 1250 (D.C. Cir. 2007).

8 40 CFR § 261.2(a)(2)(i).

9 40 CFR § 261.2(b).

10 40 CFR § 261.2(c).

11 See e.g., 40 CFR § 261.2(e).

12 For example, as early as 1987, the United States Circuit Court of Appeals for the District of Columbia held that EPA had exceeded its authority in “seeking to bring materials that are not discarded or otherwise disposed of within the meaning of waste.” American Mining Congress v. EPA,          824 F.2d 1177, 1178 (D.C. Cir. 1987).

13 See 40 CFR § 241.3.

14 40 CFR § 241.3(d)(1)(iii)

15 Letter from EPA Office of Solid Waste and Emergency Response to Trendgreen Associates LLC,  June 30, 2011.

16 Letter from EPA to Union Carbide Corp., March 15, 1974.

17 76 Fed. Reg. 15456, 15523

18 76 Fed. Reg. at 15524, 15485

19 76 Fed. Reg. at 15464.


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