Standards of Performance for New Stationary Sources and Emission Guidelines for Existing Sources: Sewage Sludge Incineration Units

Federal RegisterMar 21, 2011

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ENVIRONMENTAL PROTECTION AGENCY

40 CFR Part 60

[EPA-HQ-OAR-2009-0559; FRL-9272-9]

RIN 2060-AP90

Standards of Performance for New Stationary Sources and Emission Guidelines for Existing Sources: Sewage Sludge Incineration Units

AGENCY:

Environmental Protection Agency (EPA).

ACTION:

Final rule.

SUMMARY:

This action promulgates EPA's new source performance standards and emission guidelines for sewage sludge incineration units located at wastewater treatment facilities designed to treat domestic sewage sludge. This final rule sets limits for nine pollutants under section 129 of the Clean Air Act: Cadmium, carbon monoxide, hydrogen chloride, lead, mercury, nitrogen oxides, particulate matter, polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans, and sulfur dioxide.

DATES:

The final rule is effective on May 20, 2011. The incorporation by reference of certain publications listed in the rule is approved by the Director of the Federal Register as of May 20, 2011.

ADDRESSES:

EPA established a single docket under Docket ID No. EPA-HQ-OAR-2009-0559 for this action. This docket includes previous actions including the standards proposed on October 14, 2010 (75 FR 63260) and a supplemental notice issued on November 5, 2010 (75 FR 68296). All documents in the docket are listed on the

http://www.regulations.gov

Web site. Although listed in the index, some information is not publicly available,

e.g.,

confidential business information or other information whose disclosure is restricted by statute. Certain other material, such as copyrighted material, is not placed on the Internet and will be publicly available only in hard copy form. Publicly available docket materials are available either electronically through

http://www.regulations.gov

or in hard copy at EPA's Docket Center, Public Reading Room, EPA West Building, Room 3334, 1301 Constitution Avenue, NW., Washington, DC 20004. This Docket Facility is open from 8:30 a.m. to 4:30 p.m., Monday through Friday, excluding legal holidays. The telephone number for the Public Reading Room is (202) 566-1744, and the telephone number for the EPA Docket Center is (202) 566-1742.

FOR FURTHER INFORMATION CONTACT:

Ms. Amy Hambrick, Natural Resource and Commerce Group, Sector Policies and Programs Division (E143-03), Environmental Protection Agency, Research Triangle Park, North Carolina 27711; telephone number: (919) 541-0964; fax number: (919) 541-3470; e-mail address:

hambrick.amy@epa.gov

SUPPLEMENTARY INFORMATION:

Acronyms and Abbreviations.

The following acronyms and abbreviations are used in this document.

7-PAH 7-Polycyclic Aromatic Hydrocarbons

ANSI American National Standards Institute

As Arsenic

ASME American Society of Mechanical Engineers

ASTM American Society of Testing and Materials

CAA Clean Air Act

CASS Continuous Automated Sampling System

CBI Confidential Business Information

Cd Cadmium

CDX Central Data Exchange

CEMS Continuous Emissions Monitoring Systems

COMS Continuous Opacity Monitoring System

The Court U.S. Court of Appeals for the District of Columbia Circuit

CPMS Continuous Parametric Monitoring System

CFR Code of Federal Regulations

CISWI Commercial and Industrial Solid Waste Incineration

CO Carbon Monoxide

Cr Chromium

CWA Clean Water Act

EG Emission Guidelines

EJ Environmental Justice

ERT Electronic Reporting Tool

ESP Electrostatic Precipitators

FF Fabric Filter

FB Fluidized Bed

FGR Flue Gas Recirculation

HAP Hazardous Air Pollutants

HCl Hydrogen Chloride

Hg Mercury

HMIWI Hospital, Medical and Infectious Waste Incineration

ICR Information Collection Request

ISTDMS Integrated Sorbent Trap Dioxin Monitoring System

ISTMMS Integrated Sorbent Trap Mercury Monitoring System

LML Lowest Measured Level

MACT Maximum Achievable Control Technology

Mg/dscm Milligrams per Dry Standard Cubic Meter

MH Multiple Hearth

Mn Manganese

MWC Municipal Waste Combustion

NAAQS National Ambient Air Quality Standards

NAICS North American Industrial Classification System

Ng/dscm Nanograms per Dry Standard Cubic Meter

Ni Nickel

Nitrogen Oxides

NPRM Notice of Proposed Rulemaking

NSPS New Source Performance Standards

NTAA National Tribal Air Association

NTTAA National Technology Transfer and Advancement Act of 1995

OAQPS Office of Air Quality Planning and Standards

O&M Operation and Maintenance

OMB Office of Management and Budget

OP Office of Policy

OSWI Other Solid Waste Incineration

OTM Other Test Method

OW Office of Water

Pb Lead

PCB Polychlorinated Biphenyls

PCDD/PCDF Polychlorinated Dibenzo-P-Dioxins and Polychlorinated Dibenzofurans

PM Particulate Matter

POM Polycyclic Organic Matter

POTW Publicly Owned Treatment Works

PPM Parts per Million

PPMV Parts per Million by Volume

PPMVD Parts per Million of Dry Volume

PRA Paperwork Reduction Act

PS Performance Specifications

RCRA Resource Conservation and Recovery Act

RFA Regulatory Flexibility Act

RIA Regulatory Impact Analysis

RTO Regenerative Thermal Oxidizer

SBA Small Business Administration

SCR Selective Catalytic Reduction

SNCR Selective Non-Catalytic Reduction

Sulfur Dioxide

SSI Sewage Sludge Incineration

SSM Startup, Shutdown, and Malfunction

TEF Toxic Equivalency Factor

TEQ Toxic Equivalency

THC Total Hydrocarbons

TMB Total Mass Basis

TPD Tons per Day

TPY Tons per Year

TTN Technology Transfer Network

UL Upper Limit

UMRA Unfunded Mandates Reform Act of 1995

UPL Upper Prediction Limit

VCS Voluntary Consensus Standards

WWW Worldwide Web

Organization of This Document.

The following outline is provided to aid in locating information in this preamble.

I. General Information

A. Does the action apply to me?

B. Where can I get a copy of this document?

C. Judicial Review

II. Background

A. What is the statutory background for this final rule?

B. What are the primary sources of emissions and what are the emissions?

C. What is the relationship of the final standards to other standards for the use or disposal of sewage sludge and associated air emissions?

III. Summary of the Final Standards

A. What units are affected by the final standards?

B. What are the emission limits in the emission guidelines for existing sources?

C. What are the emission limits in the new source performance standards for new sources?

D. What are the testing and monitoring requirements?

E. What are the other requirements for new and existing SSI units?

F. What are the recordkeeping and reporting requirements?

G. What are the SSM provisions?

H. What are the Title V permit requirements?

I. What are the applicability dates of the standards?

J. What are the requirements for submission of emissions test results to EPA?

IV. Summary of Significant Changes Following Proposal

A. Applicability

B. Subcategories

C. MACT Floor UPL Calculation and EG and NSPS Emission Limits

D. Baseline Emissions, Costs, and Impacts Estimation

E. Compliance Requirements

F. Definitions

V. Significant Public Comments and Rationale for Changes to the Proposed Rule

A. Legal and Applicability Issues Regulating SSI Under Section 112 vs. Section 129

B. Subcategories

C. MACT Floor Analysis

D. Baseline Emissions

E. Beyond-the-Floor Analysis

F. Cost and Economic Impacts

G. Startup, Shutdown, and Malfunction

H. Compliance Requirements

VI. Impacts of the Final Action

A. Impacts of the Final Action for Existing Units

B. Impacts of the Final Action for New Units

VII. Statutory and Executive Order Reviews

A. Executive Order 12866 and 13563: Regulatory Planning and Review

B. Paperwork Reduction Act

C. Regulatory Flexibility Act

D. Unfunded Mandates Reform Act

E. Executive Order 13132: Federalism

F. Executive Order 13175: Consultation and Coordination With Indian Tribal Governments

G. Executive Order 13045: Protection of Children From Environmental Health and Safety Risks

H. Executive Order 13211: Actions That Significantly Affect Energy Supply, Distribution, or Use

I. National Technology Transfer and Advancement Act

J. Executive Order 12898: Federal Actions To Address Environmental Justice in Minority Populations and Low-Income Populations

I. General Information

A. Does this action apply to me?

Categories and entities potentially affected by the final action are those that operate sewage sludge incinerators (SSI). Although there is no specific NAICS code for SSI, these units may be operated by wastewater treatment facilities designed to treat domestic sewage sludge. The following NAICS codes could apply:

Category

NAICS code

Examples of potentially

regulated entities

Solid waste combustors and incinerators

562213

Municipalities with SSI units.

Sewage treatment facilities

221320

This table is not intended to be exhaustive, but rather provides a general guide for identifying entities likely to be affected by the final action. To determine whether your facility would be affected by the final action, you should examine the applicability criteria in 40 CFR 60.4770 of subpart LLLL and proposed 40 CFR 60.5005 of subpart MMMM. If you have any questions regarding the applicability of the final action to a particular entity, contact the person listed in the preceding

FOR FURTHER INFORMATION CONTACT

section.

B. Where can I get a copy of this document?

In addition to being available in the docket, an electronic copy of the final action will also be available on the WWW through the TTN. Following signature, a copy of the final action will be posted on the TTN's policy and guidance page for newly proposed or promulgated rules at the following address:

http://www.epa.gov/ttn/oarpg/.

The TTN provides information and technology exchange in various areas of air pollution control.

C. Judicial Review

Under CAA section 307(b)(1), judicial review of this final rule is available only by filing a petition for review in the Court by May 20, 2011. Section 307(d)(7)(B) of the CAA further provides that “only an objection to this final rule that was raised with reasonable specificity during the period for public comment can be raised during judicial review.” This section also provides a mechanism for EPA to convene a proceeding for reconsideration, “[i]f the person raising an objection can demonstrate to EPA that it was impracticable to raise such objection within [the period for public comment] or if the grounds for such objection arose after the period for public comment (but within the time specified for judicial review) and if such objection is of central relevance to the outcome of this rule.” Any person seeking to make such a demonstration to EPA should submit a Petition for Reconsideration to the Office of the Administrator, Environmental Protection Agency, Room 3000, Ariel Rios Building, 1200 Pennsylvania Ave., NW., Washington, DC 20004, with a copy to both of the contacts listed in the preceding

FOR FURTHER INFORMATION CONTACT

section, and the Associate General Counsel for the Air and Radiation Law Office, Office of General Counsel (Mail Code 2344A), Environmental Protection Agency, 1200 Pennsylvania Ave., NW., Washington, DC 20004. Note, under CAA section 307(b)(2), the requirements established by this final rule may not be challenged separately in any civil or criminal proceedings brought by EPA to enforce these requirements.

II. Background

A. What is the statutory background for this final rule?

Section 129 of the CAA, entitled, “Solid Waste Combustion,” requires EPA to develop and adopt standards for solid waste incineration units pursuant to CAA sections 111 and 129. Section 129(a)(1)(A) of the CAA requires EPA to establish performance standards, including emission limitations, for “solid waste incineration units.” Section 129 of the CAA defines “solid waste incineration unit” as “a distinct operating unit of any facility which combusts any solid waste material from commercial or industrial establishments or the general public” (section 129(g)(1)). Section 129 of the CAA also provides that “solid waste” shall have the meaning established by EPA pursuant to its authority under the RCRA (section 129(g)(6)). Sections 111(b) and 129(a) of the CAA address emissions from new units (

i.e.,

NSPS), and CAA sections 111(d) and 129(b) address emissions from existing units (

i.e.,

EG). The NSPS are directly enforceable Federal regulations, and under CAA section 129(f)(1), become effective 6 months after promulgation. Unlike the NSPS, the EG are not themselves directly enforceable. Rather, the EG are implemented and enforced through either an EPA-approved state plan or a promulgated Federal plan.

States are required to submit a plan to implement and enforce the EG to EPA for approval not later than 1 year after EPA promulgates the EG (CAA section 129(b)(2)). The state plan must be “at least as protective as” the EG and must ensure compliance with all applicable requirements not later than 3 years after the state plan is approved by EPA, or 5 years after promulgation of the relevant EG, whichever is sooner. EPA's procedures for submitting and approving state plans are set forth in 40 CFR part 60, subpart B. When a state plan is approved by EPA, the plan requirements become federally enforceable, but the state has primary responsibility for implementing and enforcing the plan. However, EPA is required to develop, implement, and enforce a Federal plan for solid waste incineration units located in any state which has not submitted an approvable state plan within 2o years after the date of promulgation of the relevant EG (CAA section 129(b)(3)). The Federal plan must assure that each solid waste incineration unit subject to the Federal plan is in compliance with all provisions of the EG not later than 5 years after the date the relevant guidelines are promulgated. EPA views the Federal plan as a “place-holder” that remains in effect only until such time as a state without an approved plan submits and receives EPA approval of its state plan. Once an applicable state plan has been approved, the requirements of the Federal plan no longer apply to solid waste incineration units covered by that state plan.

The CAA sets forth a two-stage approach to regulating emissions from solid waste incinerator units. The statute also provides EPA with substantial discretion to distinguish among classes, types, and sizes of incineration units within a category while setting standards. In the first stage of setting standards, CAA section 129(a)(2) requires EPA to establish technology-based emission standards that reflect levels of control EPA determines are achievable for new and existing units, after considering costs, nonair quality health and environmental impacts and energy requirements associated with the implementation of the standards. Section 129(a)(5) of the CAA then directs EPA to review those standards and revise them as necessary every 5 years. In the second stage, CAA section 129(h)(3) requires EPA to determine whether further revisions of the standards are necessary in order to provide an ample margin of safety to protect public health.

In setting forth the methodology EPA must use to establish the first-stage technology-based standards for the standards, CAA section 129(a)(2) provides that standards “applicable to solid waste incineration units promulgated under section 111 and this section shall reflect the maximum degree of reduction in emissions of [certain listed air pollutants] that the Administrator, taking into consideration the cost of achieving such emission reduction and any nonair quality health and environmental impacts and energy requirements, determines is achievable for new and existing units in each category.” This level of control is referred to as a MACT standard.

In promulgating a MACT standard, EPA must first calculate the minimum stringency levels for new and existing solid waste incineration units in a category, generally based on levels of emissions control achieved or required to be achieved by the subject units. The minimum level of stringency is called the MACT “floor,” and CAA section 129(a)(2) sets forth differing levels of minimum stringency that EPA's standards must achieve, based on whether they regulate new and reconstructed sources, or existing sources. For new and reconstructed sources, CAA section 129(a)(2) provides that the “degree of reduction in emissions that is deemed achievable * * * shall not be less stringent than the emissions control that is achieved in practice by the best controlled similar unit, as determined by the Administrator.” Emissions standards for existing units may be less stringent than standards for new units, but “shall not be less stringent than the average emissions limitation achieved by the best performing 12 percent of units in the category.”

Maximum Achievable Control Technology analyses involve an assessment of the emissions from the best performing unit or units in a source category. The assessment can be based on actual emissions data, knowledge of the air pollution control in place in combination with actual emissions data, state regulatory requirements that may enable EPA to estimate the actual performance of the regulated units, or other emissions information. For each source category, the assessment involves a review of actual emissions data with an appropriate accounting for emissions variability. Other methods of estimating emissions can also be used, if the methods can be shown to provide reasonable estimates of the actual emissions performance of a source or sources. In addition to the MACT floor limit, EPA must examine whether more stringent “beyond-the-floor” standards should be adopted. In considering whether such standards are appropriate, EPA must consider the cost of achieving such emission reduction, and any non-air quality health and environmental impacts and energy requirements. The CAA requires that the MACT floor for new sources be no less stringent than the emissions control achieved in practice by the best-controlled similar unit. EPA is also required to consider beyond-the-floor standards for new sources, consistent with the factors described above. Clean Air Act section 129(a)(1) identifies five categories of solid waste incineration units:

• Units that combust municipal waste at a capacity greater than 250 tpd.

• Units that combust municipal waste at a capacity equal to or less than 250 tpd.

• Units that combust hospital, medical, and infectious waste.

• Units that combust commercial or industrial waste.

• Units that combust waste and which are not specifically identified in section 129(a)(1)(A) through (D) are referred to in section 129(a)(1)(E) as “other categories” of solid waste incineration units.

A SSI unit is an incinerator located at a wastewater treatment facility designed to treat domestic sewage sludge that combusts sewage sludge for the purpose of reducing the volume of the sewage sludge by removing combustible matter. Sewage sludge incinerators, by virtue of having not been specifically identified in section 129(a)(1)(A) through (D), have been interpreted to be part of the broader category of “other categories” of solid waste. EPA has issued emission standards for large and small MWC, HMIWI, CISWI, and OSWI units; however, as explained further below, none of those emission standards apply to SSI units.

EPA issued emission standards for OSWI units on December 16, 2005 (70 FR 74870). Based on EPA's interpretation of the CAA at that time, the OSWI standards did not include emission standards for SSI units. EPA received a petition for reconsideration of the OSWI standards on February 14, 2006, regarding the exclusion of certain categories, including SSI.

While EPA granted the petition for reconsideration on June 28, 2006, EPA's final review, which became effective January 22, 2007, concluded that no additional changes were necessary to the 2005 OSWI rule (71 FR 36726). That litigation is currently being held in abeyance. EPA currently intends to revise the emission standards for OSWI units in the future,

and that rulemaking will address all OSWI units except SSI units.

Sierra Club

EPA;

DC Cir. Nos. 06-1066, 07-1063.

In the OSWI rule issued on December 16, 2005, EPA stated that it had decided not to regulate SSI units under CAA section 129 (70 FR 74870), but rather to regulate SSI units under CAA section 112, pointing to a statement in EPA's 2000 Unified Regulatory Agenda stating that sewage sludge incinerators do not combust waste from a commercial or industrial establishment or the general public. We declined to revise that decision to regulate SSI units under 112 in the response to the petition for reconsideration on this issue for five reasons, including our position that section 129(a)(1)(E) did not require regulation of all “other” solid waste incineration units and that section 129(g)(1)'s enumerated exemptions to the definition of “solid waste incineration unit” were not exclusive, and that section 129(h)(2) gave EPA the discretion to choose whether to regulate incinerators under section 112 or section 129 of the Act. (72 FR 2620). In June 2007, in a separate decision related to EPA's December 1, 2000, emission standards for CISWI units, the Court held that any unit combusting any solid waste must be regulated under section 129 of the CAA. The impact of this decision on EPA's regulation of SSI is explained in detail in the NPRM.

NRDC

EPA;

489 F. 3d. at 1257-8.

EPA considers SSI units to be “other solid waste incineration units,” since that category is intended to encompass all solid waste incineration units that are not included in the first four categories identified in CAA section 129(a) through (d). EPA plans to re-issue emission standards for the remaining OSWI units at a later time. EPA is taking final action on emission standards for SSI units at this time because these emission standards are needed as part of EPA's fulfillment of its obligations under CAA sections 112(c)(3) and (k)(3)(B)(ii) and section 112(c)(6). Clean Air Act section 112(k)(3)(B)(ii) calls for EPA to identify at least 30 HAP which, as the result of emissions from area sources, pose the greatest threat to public health in the largest number of urban areas. EPA must then ensure that sources representing 90 percent of the aggregate area source emissions of each of the 30 identified HAP are subject to standards pursuant to section 112(d).

Sewage sludge incineration units are one of the source categories identified for regulation to meet the 90 percent requirement for Cd, Cr, Pb, Mn, Hg, Ni and PCB. EPA is ordered by the Court to satisfy its obligation under CAA section 112(c)(3) and (k)(3)(B)(ii) by January 16, 2011.

CAA section 112(c)(3) and section 112(k)(3)(B)(ii).

Sierra Club

Jackson;

D.DC No. 1:01CV01537.

In a notice on April 10, 1998, EPA provided a list of source categories for regulation under CAA section 112(d)(2) or 112(d)(4). Section 112(c)(6) of the CAA requires EPA to identify categories of sources of seven specified pollutants to assure that sources counting for not less than 90 percent of the aggregate emissions of each such pollutant are subject to standards under CAA section 112(d)(2) or 112(d)(4) (63 FR 17838). Sewage sludge incineration units are one of the identified source categories for regulation to meet the 90 percent requirement for Hg. Further information can be found in the Memorandum titled, “Emission Standards for Meeting the Ninety Percent Requirement under Section 112(c)(6) of the Clean Air Act” in the SSI docket (EPA-HQ-OAR-2009-0559).Therefore, EPA is finalizing the SSI standards prior to taking action on the remaining source categories that will be regulated under CAA section 129(a)(1)(E) as OSWI units.

B. What are the primary sources of emissions and what are the emissions?

Sewage sludge incineration units may be operated by municipalities or other entities. Incineration continues to be used to dispose of sewage sludge. Combustion of solid waste, and specifically sewage sludge, causes the release of a wide array of air pollutants, some of which exist in the waste feed material and are released unchanged during combustion, and some of which are generated as a result of the combustion process itself. The pollutants for which numerical limits must be established, as specified in section 129 of the CAA, include Cd, CO, HCl, Hg, NO

, PCDD/PCDF, PM, Pb, and SO

; and, where appropriate, numerical limits for opacity must also be established. These emissions come from the SSI unit's stack and fugitive PM emissions, as indicated by the associated visible emissions, also occur from ash handling.

C. What is the relationship of the final standards to other standards for the use or disposal of sewage sludge and associated air emissions?

Under authority of section 405(d) and (e) of the CWA, as amended 33 U.S.C.A. 1251, (

et seq.

), EPA promulgated regulations on February 19, 1993, at 40 CFR part 503 designed to protect public health and the environment from any reasonably anticipated adverse effects of certain pollutants that may be present in sewage sludge. The part 503 regulations establish requirements for the final use and disposal of sewage sludge when: (1) The sludge is applied to the land for a beneficial use (

e.g.,

for use in home gardens); (2) the sludge is disposed on land by placing it on surface disposal sites; and (3) the sewage sludge is incinerated. The standards apply to POTW that generate or treat domestic sewage sludge, as well as to any person who uses or disposes of sewage sludge from such treatment works.

The part 503 requirements for firing sewage sludge in a SSI are in subpart E of the regulations. Subpart E includes general requirements; pollutant limits; operational standards; management practices; and monitoring, recordkeeping, and reporting requirements.

These part 503 regulations require that SSI meet the National Emission Standards for Beryllium and Hg in subparts C and E, respectively, of 40 CFR part 61. The regulations also require that the allowable concentration of five other inorganic pollutants be calculated using equations in the regulation. The inorganic pollutants included are Pb, As, Cd, Cr, and Ni. The terms in the equations must be determined on a case-by-case basis, except for the risk-specific concentration for the inhalation exposure pathway to protect individuals when these pollutants are inhaled. The site-specific variables for the equations (incinerator type, dispersion factor, control efficiency, feed rate, and stack height) must be used to calculate allowable daily concentrations of As, Cd, Cr, Pb and Ni in the sewage sludge fed to the incinerator.

Also included in subpart E of part 503 is an operational standard for THC. The value for THC in the final part 503 regulation cannot be exceeded in the exit gas from the SSI stack. Management practices and frequency of monitoring, recordkeeping, and reporting requirements are also included in this subpart.

Under today's final standards, EPA is establishing limits for three of the inorganic pollutants covered by the current part 503 regulations (Cd, Pb and Hg) and the following six additional pollutants: HCl, CO, NO

, SO

, PM, and total PCDD/PCDF. Besides the pollutants covered here, there are other differences between the part 503 regulations and these final standards. The emission limits for inorganic pollutants under part 503 are risk-based numbers rather than technology-based. Also, part 503 does not distinguish between new and existing units or between incinerator types (

i.e.,

MH or

FB incinerator) for setting emission limits since emission limits are based on risks to a highly exposed individual.

Because both part 503 and these final standards cover the same universe of facilities, there are certain issues that arise in terms of potential impacts to current SSI facilities. First, the regulation of sewage sludge under CAA section 129 will result in stricter emission standards than under the current CWA rule. Additional pollution controls will increase costs for facilities that continue to use the incineration disposal method. If the additional costs are high enough, many entities may choose to adopt alternative disposal methods (

e.g.,

surface disposal in landfills or other beneficial land applications). Consequently, a potential impact of this rule is that some of the estimated 110 facilities that operate SSI as the primary means of disposal could discontinue this practice and would instead landfill or land apply their sewage sludge. Second, one must consider the available capacity of surface disposal sites to receive additional sewage sludge and the potential for added costs if the use of SSI is discontinued. Third, SSI will be subject to two different sets of requirements (numeric standards, operational standards, monitoring, recordkeeping, and reporting) under the two different statutes, creating an additional burden to these facilities unless alternative regulatory approaches are implemented. EPA plans to evaluate the requirements under both statutes to determine what changes, if any, should be made to the part 503 regulations.

III. Summary of the Final Standards

This preamble discusses the final standards as they apply to the owner or operator of a new or existing SSI unit. This preamble also describes the major requirements of the SSI regulations. For a full description of the final requirements and compliance times, see the SSI standards in subparts LLLL and MMMM.

A. What units are affected by the final standards?

The final standards and guidelines apply to owners or operators of SSI units (as defined in 40 CFR 60.4780 and 40 CFR 60.5065) located at wastewater treatment facilities designed to treat domestic sewage sludge. A SSI unit is an enclosed device or devices using controlled flame combustion that burns sewage sludge for the purpose of reducing the volume of the sewage sludge by removing combustible matter. A SSI unit also includes, but is not limited to, the sewage sludge feed system, auxiliary fuel feed system, grate system, flue gas system, waste heat recovery equipment, if any, and bottom ash system. The SSI unit includes all ash handling systems connected to the bottom ash handling system. The combustion unit bottom ash system ends at the truck loading station or similar equipment that transfers the ash to final disposal. The SSI unit does not include air pollution control equipment or the stack. The affected facility is each individual SSI unit. The SSI standards in subparts LLLL and MMMM apply to new and existing SSI units that burn sewage sludge as defined in the subparts. The final standards define two subcategories for new and existing SSI units: MH incinerators and FB incinerators.

The combustion of sewage sludge that is not burned in a SSI unit located at a wastewater treatment facility designed to treat domestic sewage sludge is subject to other section 129 standards, such as the CISWI standards (40 CFR part 60, subparts CCCC and DDDD of this part), the OSWI standards (40 CFR part 60, subparts EEEE and FFFF), the MWC standards (40 CFR part 60, subparts Ea, Eb, Cb, AAAA, and BBBB of this part) or the Hazardous Waste Combustor rule (40 CFR part 63 subpart EEE).

B. What are the emission limits in the emission guidelines for existing sources?

The final emission limits for existing sources in the MH incinerator subcategory and FB incinerator subcategory are presented in Table 1 of this preamble. Existing sources may comply with either the PCDD/PCDF TEQ or TMB emission limits.

These standards apply at all times.

Table 1—Emission Limits for Existing SSI Units

Pollutant

Units

Emission limit for MH incinerators

Emission limit for FB incinerators

mg/dscm @ 7% O

0.095

0.0016

ppmvd @ 7% O

3,800

HCl

ppmvd @ 7% O

1.2

0.51

mg/dscm @ 7% O

0.28

0.037

ppmvd @ 7% O

220

150

mg/dscm @ 7% O

0.30

0.0074

PCDD/PCDF, TEQ

ng/dscm @ 7% O

0.32

0.10

PCDD/PCDF, TMB

ng/dscm @ 7% O

5.0

1.2

mg/dscm @ 7% O

ppmvd @ 7% O

C. What are the emission limits in the new source performance standards for new sources?

The final emission limits for new sources in the MH incinerator subcategory and FB incinerator subcategory are presented in Table 2 of this preamble. Existing sources may comply with either the PCDD/PCDF TEQ or TMB emission limits.

These standards apply at all times.

Table 2—Emission Limits for New SSI Units

Pollutant

Units

Emission limit for MH incinerators

Emission limit for FB incinerators

mg/dscm @ 7% O

0.0024

0.0011

ppmvd @ 7% O

HCl

ppmvd @ 7% O

1.2

0.24

mg/dscm @ 7% O

0.15

0.0010

ppmvd @ 7% O

210

mg/dscm @ 7% O

0.0035

0.00062

PCDD/PCDF, TMB

ng/dscm @ 7% O

0.045

0.013

PCDD/PCDF, TEQ

ng/dscm @ 7% O

0.0022

0.0044

mg/dscm @ 7% O

9.6

ppmvd @ 7% O

5.3

D. What are the testing and monitoring requirements?

These final standards require all new and existing SSI units to demonstrate initial and annual compliance with the emission limits using EPA-approved emission test methods. The final standards also provide an option for less frequent testing if sources demonstrate that their emissions of regulated pollutants are below thresholds of the emission limits.

For existing SSI units, the EG requires initial and annual emissions performance tests (or continuous emissions monitoring or continuous sampling as an alternative), bag leak detection systems for FF controlled units, continuous parameter monitoring, and annual inspections of air pollution control devices, if they are used to meet the emission limits. Additionally, existing units are required to conduct Method 22 (

see

40 CFR part 60, appendix A-7) visible emissions test of the ash handling operations during each compliance test.

For new SSI units, the NSPS requires initial and annual emissions performance tests (or continuous emissions monitoring or continuous sampling as an alternative), bag leak detection systems for FF controlled units, as well as continuous parameter monitoring and annual inspections of air pollution control devices that may be used to meet the emission limits. The final rule requires all new SSI units to install a CO CEMS. Operators of new units are also required to conduct Method 22 visible emissions testing of the ash handling operations during each compliance test.

For existing SSI units, use of Cd, CO, HCl, NO

, PM, Pb or SO

CEMS; ISTMMS; and ISTDMS (continuous sampling with periodic sample analysis) are approved alternatives to parametric monitoring and annual compliance testing. For new SSI units, CO CEMS are required, and use of Cd, HCl, NO

, PM, Pb or SO

CEMS; ISTMMS; and ISTDMS (continuous sampling, with periodic sample analysis) are approved alternatives to parametric monitoring and annual compliance testing.

E. What are the other requirements for new and existing SSI units?

Owners or operators of new or existing SSI units are required to meet operator training and qualification requirements, which include: Ensuring that at least one operator or supervisor per facility complete the operator training course, that qualified operator(s) or supervisor(s) complete an annual review or refresher course specified in the regulation, and that they maintain plant-specific information, updated annually, regarding training.

Owners or operators of new SSI units are required to conduct a siting analysis, which includes submitting a report that evaluates site-specific air pollution control alternatives that minimize potential risks to public health or the environment, considering costs, energy impacts, non-air environmental impacts and any other factors related to the practicability of the alternatives.

Owners or operators of new or existing SSI units are required to submit a monitoring plan for any continuous monitoring system or bag leak detection system used to comply with the rule. They must also submit a monitoring plan for their ash handling system that specifies the operating procedures they will follow to ensure that they meet the fugitive emission limit.

F. What are the recordkeeping and reporting requirements?

Records of the initial and all subsequent stack or PS tests, deviation reports, operating parameter data, continuous monitoring data, maintenance and inspections of the air pollution control devices, the siting analysis (for new units only), monitoring plan and operator training and qualification must be maintained for 5 years. The results of the stack tests and PS tests and values for operating parameters are required to be included in initial and subsequent compliance reports.

G. What are the SSM provisions?

The Court vacated portions of two provisions in EPA's CAA section 112 regulations governing the emissions of HAP during periods of SSM.

Sierra Club

EPA,

551 F.3d 1019 (D.C. Cir. 2008), cert. denied, 130 S. Ct. 1735 (U.S. 2010). Specifically, the Court vacated the SSM exemption contained in 40 CFR 63.6(f)(1) and 40 CFR 63.6(h)(1), (the “General Provisions Rule,”) that EPA promulgated under section 112 of the CAA. When incorporated into CAA section 112(d) regulations for specific source categories, these two provisions exempt sources from the requirement to comply with the otherwise applicable CAA section 112(d) emission standard during periods of SSM.

While the Court's ruling in

Sierra Club

EPA

directly affects only the subset of CAA section 112(d) rules that incorporate 40 CFR 63.6(f)(1) and (h)(1) by reference and that contain no other regulatory text exempting or excusing compliance during SSM events, the legality of source category-specific SSM provisions is questionable.

Consistent with

Sierra Club

EPA,

EPA is requiring that emission limitations in these final standards apply at all times the unit is operating. In establishing these standards, EPA has taken into account startup and shutdown periods and, for the reasons explained below, has not established different standards for those periods.

We are not promulgating a separate emission standard for the source category that applies during periods of startup and shutdown. Based on the information available at this time, we believe that SSI units will be able to meet the emission limits during periods of startup. Units we have information on use natural gas, landfill gas, or distillate oil to start the unit and add waste once the unit has reached combustion temperatures. Emissions from burning natural gas, landfill gas or distillate fuel oil are expected to generally be lower than from burning solid wastes. Emissions during periods of shutdown are also generally lower than emissions during normal operations because the

materials in the incinerator would be almost fully combusted before shutdown occurs. Furthermore, the approach for establishing MACT floors for SSI units ranked individual SSI units based on actual performance for each pollutant and subcategory, with an appropriate accounting of emissions variability. Because we accounted for emissions variability, we believe we have adequately addressed any minor variability that may potentially occur during startup or shutdown.

Periods of startup, normal operations, and shutdown are predictable and routine aspects of a source's operations. However, by contrast, malfunction is defined as a “sudden, infrequent, and not reasonably preventable failure of air pollution control and monitoring equipment, process equipment or a process to operate in a normal or usual manner * * * ” (40 CFR 60.2). EPA has determined that malfunctions should not be viewed as a distinct operating mode and, therefore, any emissions that occur at such times do not need to be factored into development of CAA section 129 standards, which, once promulgated, apply at all times. Nothing in CAA section 129 or in case law requires that EPA anticipate and account for the innumerable types of potential malfunction events in setting emission standards.

See, Weyerhaeuser

Costle,

590 F.2d 1011, 1058 (DC Cir. 1978) (“In the nature of things, no general limit, individual permit, or even any upset provision can anticipate all upset situations. After a certain point, the transgression of regulatory limits caused by `uncontrollable acts of third parties,' such as strikes, sabotage, operator intoxication or insanity, and a variety of other eventualities, must be a matter for the administrative exercise of case-by-case enforcement discretion, not for specification in advance by regulation.”).

Further, it is reasonable to interpret CAA section 129 as not requiring EPA to account for malfunctions in setting emissions standards. For example, we note that CAA section 129 uses the concept of “best controlled” or “best performing” sources in defining MACT, the level of stringency that major source standards must meet. Applying the concept of “best controlled” or “best performing” to a source that is malfunctioning presents significant difficulties. The goal of best controlled or best performing sources is to operate in such a way as to avoid malfunctions of their units.

Moreover, even if malfunctions were considered a distinct operating mode, we believe it would be impracticable to take malfunctions into account in setting CAA section 129 standards for SSI. As noted above, by definition, malfunctions are sudden and unexpected events, and it would be difficult to set a standard that takes into account the myriad different types of malfunctions that can occur across all sources in the category. Moreover, malfunctions can vary in frequency, degree, and duration, further complicating standard setting.

For the SSI standards, malfunctions are required to be reported in deviation reports. We will then review the deviation reports to determine if the deviation is a violation of the standards.

In the event that a source fails to comply with the applicable CAA section 129 standards as a result of a malfunction event, EPA would determine an appropriate response based on, among other things, the good faith efforts of the source to minimize emissions during malfunction periods, including preventative and corrective actions, as well as root cause analyses to ascertain and rectify excess emissions. EPA would also consider whether the source's failure to comply with the CAA section 129 standard was, in fact, “sudden, infrequent, not reasonably preventable” and was not instead “caused in part by poor maintenance or careless operation.”

40 CFR 60.2 (definition of malfunction).

Finally, EPA recognizes that even equipment that is properly designed and maintained can fail and that such failure can sometimes cause an exceedance of the relevant emission standard.

EPA is therefore finalizing the proposed affirmative defense to civil penalties for exceedances of emissions limits that are caused by malfunctions, with some revisions to the proposed regulatory provision.

Under this provision, the source must prove by a preponderance of the evidence that it has met all of the elements set forth in 40 CFR 60.4860 and in 40 CFR 60.5180. The criteria ensure that the affirmative defense is available only where the event that causes an exceedance of the emission limit meets the narrow definition of malfunction in 40 CFR 60.2 (sudden, infrequent, not reasonable preventable and not caused by poor maintenance and or careless operation). For example, to successfully assert the affirmative defense, the source must prove by a preponderance of the evidence that excess emissions “[w]ere caused by a sudden, infrequent, and unavoidable failure of air pollution control and monitoring equipment, process equipment, or a process to operate in a normal or usual manner * * *.” The criteria also are designed to ensure that steps are taken to correct the malfunction, to minimize emissions in accordance with 40 CFR part 60, subpart LLLL and 40 CFR part 60, subpart MMMM and to prevent future malfunctions. For example, the source must prove by a preponderance of the evidence that “[r]epairs were made as expeditiously as possible when the applicable emission limitations were being exceeded * * *” and that “[a]ll possible steps were taken to minimize the impact of the excess emissions on ambient air quality, the environment and human health * * *.” In any judicial or administrative proceeding, the Administrator may challenge the assertion of the affirmative defense and, if the respondent has not met its burden of proving all of the requirements in the affirmative defense, appropriate penalties may be assessed in accordance with section 113 of the CAA (

see

also 40 CFR 22.77).

See, e.g.,

State Implementation Plans: Policy Regarding Excessive Emissions During Malfunctions, Startup, and Shutdown (Sept. 20, 1999); Policy on Excess Emissions During Startup, Shutdown, Maintenance, and Malfunctions (Feb. 15, 1983).

See

proposed definition 40 CFR 60.4930 and 40 CFR 60.5250 (defining “affirmative defense” to mean, in the context of an enforcement proceeding, a response or defense put forward by a defendant, regarding which the defendant has the burden of proof, and the merits of which are independently and objectively evaluated in a judicial or administrative proceeding).

H. What are the Title V permit requirements?

All new and existing SSI units regulated by the final SSI rule are required to apply for and obtain a Title V permit. These Title V operating permits assure compliance with all applicable requirements for regulated SSI units, including all applicable CAA section 129 requirements.

40 CFR 70.6(a)(1), 70.2, 71.6(a)(1) and 71.2.

The permit application deadline for a CAA section 129 source applying for a Title V operating permit depends on when the source first becomes subject to the relevant Title V permits program. If a regulated SSI unit is a new unit and is not subject to an earlier permit application deadline, a complete Title V permit application must be submitted on or before the relevant date below.

• For a SSI unit that commenced operation as a new source on or before the promulgation date of 40 CFR part 60, subpart LLLL, the source must submit a complete Title V permit application no later than 12 months after the promulgation date of 40 CFR part 60, subpart LLLL; or

• For a SSI unit that commences operation as a new source after the promulgation of 40 CFR part 60, subpart LLLL, the source must submit a complete Title V permit application no

later than 12 months after the date the SSI unit commences operation as a new source.

CAA section 503(c) and 40 CFR 70.5(a)(1)(i) and 71.5(a)(1)(i).

If the SSI unit is an existing unit and is not subject to an earlier permit application deadline, then the source must submit a complete Title V permit application by the earlier of the following dates:

• Twelve months after the effective date of any applicable EPA-approved CAA section 111(d)/129 plan (

i.e.,

an EPA approved state or tribal plan that implements the SSI EG); or

• Twelve months after the effective date of any applicable Federal plan; or

• Thirty-six months after promulgation of 40 CFR part 60, subpart MMMM.

For any existing SSI unit not subject to an earlier permit application deadline, the application deadline of 36 months after the promulgation of 40 CFR part 60, subpart MMMM, applies regardless of whether or when any applicable Federal plan is effective, or whether or when any applicable state or tribal CAA section 111(d)/129 plan is approved by EPA and becomes effective. (

See

CAA sections 129(e), 503(c), 503(d), and 502(a) and 40 CFR 70.5(a)(1)(i) and 71.5(a)(1)(i).)

If the SSI unit is subject to Title V as a result of some triggering requirement(s) other than those mentioned above, for example, a SSI unit may be a major source (or part of a major source), then you may be required to apply for a Title V permit prior to the deadlines specified above. If more than one requirement triggers a source's obligation to apply for a Title V permit, the 12-month time frame for filing a Title V permit application is triggered by the requirement which first causes the source to be subject to Title V.

CAA section 503(c) and 40 CFR 70.3(a) and (b), 70.5(a)(1)(i), 71.3(a) and (b) and 71.5(a)(1)(i).

For additional background information on the interface between CAA section 129 and Title V, including EPA's interpretation of section 129(e), information on updating existing Title V permit applications and reopening existing Title V permits, see the final “Federal Plan for Commercial and Industrial Solid Waste Incineration,” October 3, 2003 (68 FR 57518), as well as the “Summary of Public Comments and Responses” document in the OSWI docket (EPA-HQ-OAR-2003-0156).

I. What are the applicability dates of the standards?

New SSI units that commence construction after October 14, 2010, or that are modified 6 months or more after the date of promulgation, must meet the NSPS emission limits of 40 CFR part 60, subpart LLLL within 6 months after the promulgation date of the standards or upon startup, whichever is later.

Under the final EG, and consistent with CAA section 129 (b)(2) and 40 CFR 60, subpart B, states are required to submit state plans containing the existing source emission limits of subpart MMMM of this part, and other requirements to implement and enforce the EG within 1 year after promulgation of the EG. States must submit state plans to EPA by March 21, 2012. State plans apply to existing SSI in the state (including SSI that are modified prior to and including the date 6 months after promulgation) and must be at least as protective as the EG.

The final EG requires existing SSI to demonstrate compliance with the standards as expeditiously as practicable after approval of a state plan, but no later than 3 years from the date of approval of a state plan or 5 years after promulgation of the EG, whichever is earlier. Consistent with CAA section 129, EPA expects states to require compliance as expeditiously as practicable. However, because we believe that many SSI units will find it necessary to retrofit existing emissions control equipment and/or install additional emissions control equipment in order to meet the final limits, EPA anticipates that states may choose to provide the 3-year compliance period allowed by CAA section 129(f)(2). If EPA does not approve a state plan or issue a Federal plan, then the compliance date is 5 years from the date of the final rule.

EPA intends to develop a Federal plan that will apply to existing SSI units in any state that has not submitted an approved state plan within 2 years after promulgation of the EG. The final EG allows existing SSI units subject to the Federal plan up to 5 years after promulgation of the EG to demonstrate compliance with the standards, as allowed by CAA section 129(b)(3).

J. What are the requirements for submission of emissions test results to EPA?

EPA must have performance test data to conduct effective reviews of CAA sections 112 and 129 standards, as well as for many other purposes including compliance determinations, emission factor development, and annual emission rate determinations. In conducting these required reviews, EPA has found it ineffective and time consuming, not only for us, but also for regulatory agencies and source owners and operators to locate, collect, and submit emissions test data because of varied locations for data storage and varied data storage methods. One improvement that has occurred in recent years is the availability of stack test reports in electronic format as a replacement for cumbersome paper copies.

In this final rule, EPA is taking a step to improve data accessibility and increase the ease and efficiency of reporting for sources. Owners and operators of SSI facilities are required to submit, to EPA's ERT database, electronic copies of reports of certain performance tests required under the SSI EG and NSPS. Data entry will be through an electronic emissions test report structure called the Emissions Reporting Tool (ERT) whenever conducting performance tests. The ERT was developed with input from stack testing companies who generally collect and compile performance test data electronically and offices within state and local agencies that perform field test assessments. The ERT is currently available at

http://www.epa.gov/ttn/chief/ert/ert_tool.html,

and access to direct data submittal to EPA's electronic emissions database (WebFIRE) will become available by December 31, 2011.

The requirement to submit source test data electronically to EPA would not require any additional performance testing and would apply to those performance tests conducted using test methods that are supported by the ERT. The ERT contains a specific electronic data entry form for most of the commonly used EPA reference methods. The Web site listed below contains a listing of the pollutants and test methods supported by the ERT. In addition, when a facility submits performance test data to WebFIRE, there will be no additional requirements for emissions test data compilation. Moreover, we believe industry will benefit from development of improved emission factors, fewer follow-up information requests, and better regulation development as discussed below. The information to be reported is already required for the existing test methods and is necessary to evaluate the conformance to the test method.

One major advantage of submitting source test data through the ERT is a standardized method to compile and store much of the documentation required to be reported by this rule that also clearly states what testing information would be required. Another important benefit of submitting these data to EPA at the time the source test is conducted is that it should substantially reduce the effort involved

in data collection activities in the future. When EPA has source category performance test data in hand, there will likely be fewer or less substantial data collection requests in conjunction with prospective required residual risk assessments or technology reviews. This results in a reduced burden on both affected facilities (in terms of reduced manpower to respond to data collection requests) and EPA (in terms of preparing and distributing data collection requests and assessing the results).

State/local/tribal agencies may also benefit in that their review may be more streamlined and accurate because they would not have to re-enter the data to assess the calculations and verify the data entry. Finally, another benefit of submitting these data to WebFIRE electronically is that these data will greatly improve the overall quality of the existing and new emission factors by supplementing the pool of emissions test data upon which the emission factor is based and by ensuring that data are more representative of current industry operational procedures. A common complaint heard from industry and regulators is that emissions factors are outdated or not representative of a particular source category. Receiving and incorporating data for most performance tests will ensure that emissions factors, when updated, represent accurately the most current range of operational practices. In summary, in addition to supporting regulation development, control strategy development, and other air pollution control activities, receiving test data already collected and using them in the emissions factors development program will save industry, state/local/tribal agencies, and EPA significant time, money, and effort while improving the quality of emission inventories and related regulatory decisions.

As mentioned earlier, the electronic database that will be used is EPA's WebFIRE, which is a Web site accessible through EPA's TTN Web. The WebFIRE Web site was constructed to store emissions test data for use in developing emission factors. A description of the WebFIRE database can be found at

http://cfpub.epa.gov/oarweb/index.cfm?action=fire.main.

The ERT will be able to transmit the electronic report through EPA's CDX network for storage in the WebFIRE database. Although ERT is not the only electronic interface that can be used to submit source test data to the CDX for entry into WebFIRE, it makes submittal of data very straightforward and easy. A description of the ERT can be found at

http://www.epa.gov/ttn/chief/ert/ert_tool.html.

IV. Summary of Significant Changes Following Proposal

EPA received over 90 public comments on the proposed rulemaking. Furthermore, we conducted one public hearing to allow the public to comment on the proposed rulemaking. After consideration of public comments received, EPA is making several changes to the standards. Following are the major changes to the standards since the proposal. The rationale for these and any other significant changes can be found in section V of this preamble or in the “Sewage Sludge Incineration (SSI) Rule: Summary of Public Comments and Responses” in the SSI docket (EPA-HQ-OAR-2009-0559).

A. Applicability

The final rule clarifies that, if any amount of sewage sludge is burned in an incinerator at a wastewater treatment facility designed to treat domestic sewage sludge, the incinerator is subject to the SSI standards in subparts LLLL and MMMM of this part while burning sewage sludge. The final rule also clarifies that sewage sludge that is not burned in a SSI located at a wastewater treatment facility designed to treat domestic sewage sludge is subject to other section 129 standards, such as the CISWI standards (40 CFR part 60, subparts CCCC and DDDD of this part), the OSWI standards (40 CFR part 60, subparts EEEE and FFFF), the MWC standards (40 CFR part 60, subparts Ea, Eb, Cb, AAAA, and BBBB of this part) or the Hazardous Waste Combustor rule (40 CFR part 63 subpart EEE).

B. Subcategories

The proposed NSPS did not subcategorize new sources. In the final NSPS, SSI units at new sources are subcategorized into two subcategories: MH and FB.

C. MACT Floor UPL Calculation and EG and NSPS Emission Limits

At proposal, we used a 99 percent UPL calculation to determine variability. For the final rule, for existing FB units, we are using a weighted 99 percent UPL calculation to account for the biasing of emissions data from one facility. The weighted UPL was not used for MH units.

In the proposed rule, two statistical measures, skewness and kurtosis, were examined to determine if the data used to calculate the MACT floor were normally or log-normally distributed. If both the reported values and the natural-log transformed reported values had skewness and kurtosis statistics that indicated neither were normally distributed, the reported dataset was selected as the basis of the floor to be conservative. If the results of the skewness and kurtosis hypothesis tests were mixed for the reported values and the natural log-transformed reported values, the analysis done on the reported data values was chosen to be conservative. We have modified our assumptions when results of the skewness and kurtosis tests do not clearly show whether a normal or log-normal distribution better represents the data, or when there are not enough data to complete the skewness and kurtosis tests. In these cases, we have chosen to use the log-normal results for the final MACT floor calculation.

In the proposed rule, we proposed setting beyond-the-floor emission standards for Hg emissions from existing MH units. In the final rule, we are establishing MACT floor emission limits but are not setting beyond-the-floor standards. Also, we are not finalizing the proposed opacity limits. At proposal, we set emission limits for both PCDD/PCDF TMB and PCDD/PCDF TEQ and required SSI units to meet both limits. In the final standards, we are allowing affected sources to comply with either the PCDD/PCDF TMB or TEQ emission limits.

In the proposed rule, we did not compare the CO span of the test to the measured CO values to determine if the values were consistent. For the final rule, we reviewed the CO values obtained from emission test reports to determine whether the span of the test used was capable of accurately reading the reported value. If the span was inconsistent with the reported value, the CO levels were adjusted to provide a value that was more consistent with the span. We revised the CO limits based on the results of this analysis.

The final emission limits resulting from the revised MACT floor calculations are presented in Tables 3 through 6 of this preamble, and compared to the proposed emission limits.

Table 3—Final and Proposed Emission Limits for Existing FB SSI Units

Pollutant

Units

Proposed

emission limit

Final emission limit

mg/dscm @ 7% O

0.0019

0.0016

ppmvd @ 7% O

HCl

ppmvd @ 7% O

0.49

0.51

mg/dscm @ 7% O

0.0033

0.037

ppmvd @ 7% O

150

mg/dscm @ 7% O

0.0098

0.0074

PCDD/PCDF, TEQ

ng/dscm @ 7% O

0.056

0.10

PCDD/PCDF, TMB

ng/dscm @ 7% O

0.61

1.2

mg/dscm @ 7% O

ppmvd @ 7% O

Table 4—Final and Proposed Emission Limits for Existing MH SSI Units

Pollutant

Units

Proposed

emission limit

Final emission limit

mg/dscm @ 7% O

0.095

ppmvd @ 7% O

3,900

3,800

HCl

ppmvd @ 7% O

1.0

1.2

mg/dscm @ 7% O

0.02

0.28

ppmvd @ 7% O

210

220

mg/dscm @ 7% O

0.30

PCDD/PCDF, TEQ

ng/dscm @ 7% O

0.32

PCDD/PCDF, TMB

ng/dscm @ 7% O

5.0

mg/dscm @ 7% O

ppmvd @ 7% O

Table 5—Final and Proposed Emission Limits for New FB SSI Units

Pollutant

Units

Proposed

emission limit

Final emission limit

mg/dscm @ 7% O

0.00051

0.0011

ppmvd @ 7% O

7.4

HCl

ppmvd @ 7% O

0.12

0.24

mg/dscm @ 7% O

0.0010

ppmvd @ 7% O

mg/dscm @ 7% O

0.00053

0.00062

PCDD/PCDF, TEQ

ng/dscm @ 7% O

0.0022

0.0044

PCDD/PCDF, TMB

ng/dscm @ 7% O

0.024

0.013

mg/dscm @ 7% O

4.1

9.6

ppmvd @ 7% O

2.0

5.3

Table 6—Final and Proposed Emission Limits for New MH SSI Units

Pollutant

Units

Proposed

emission limit

Final emission limit

mg/dscm @ 7% O

0.00051

0.0024

ppmvd @ 7% O

7.4

HCl

ppmvd @ 7% O

0.12

1.2

mg/dscm @ 7% O

0.0010

0.15

ppmvd @ 7% O

210

mg/dscm @ 7% O

0.00053

0.0035

PCDD/PCDF, TEQ

ng/dscm @ 7% O

0.0022

PCDD/PCDF, TMB

ng/dscm @ 7% O

0.024

0.045

mg/dscm @ 7% O

4.1

ppmvd @ 7% O

2.0

D. Baseline Emissions, Costs and Impacts Estimation

For the final rule, we have revised the baseline emissions, costs, and impacts to incorporate information provided by commenters. A discussion of the changes is presented in section V of this preamble. The results of these analyses are summarized in section VI of this preamble.

E. Compliance Requirements

For both the standards, the following changes have been made:

• SSI units must submit (at least 60 days before their initial compliance test date) a monitoring plan to establish that

their ash handling system will meet the visible emissions limit on a continuous basis.

• The alternative to test less frequently (every third year) is being revised to be the following:

○ If SSI units demonstrate emissions below a specified threshold during two consecutive performance tests, they may test every 3 years instead of annually. Any year that the emission threshold is not met, the SSI must test annually until the threshold is met over a consecutive 2 year period. The alternative in the standards no longer requires that SSI units establish that they meet the lower thresholds for three consecutive years.

○ For all pollutants, less frequent testing is allowed if emissions are no greater than an emissions threshold of 75 percent of the emission limit.

○ For fugitive emissions from ash handling, less frequent testing is allowed as long as visible emissions of combustion ash occur less than or equal to two percent of each hourly observation period (the standard is five percent of each of three hourly observation periods).

• The final rule removes the requirements in the standards to maintain sludge feed rate and moisture content within specified parameters. However, sludge feed rate and sludge moisture content are still required to be monitored during performance test runs, and daily records of sludge feed rate and sludge moisture content are required to be kept.

• At proposal, operating limits were calculated based on a specified percentage of the average parameter value recorded during pollutant performance tests. In the final standards, operating parameter limits are determined on a site-specific basis as the minimum or maximum operating parameter value for the parameter, as applicable, recorded during pollutant performance tests.

• The proposed standards schedule for conducting annual performance tests was each 10-12 months. This has been changed to specify that performance tests must be conducted on a calendar year basis (no less than nine calendar months and no more than 15 calendar months following the previous performance test); and you must complete five performance tests for each such pollutant in each 5-year calendar period.

• The averaging time for demonstrating compliance with the CO CEMS operating parameters has been changed from a 4-hour rolling averaging period to a 24-hr block averaging period. The averaging times for all other operating parameters, except scrubber liquid pH, has been changed from a 4-hour rolling averaging period to a 12-hour block averaging period.

• During each compliance test run, SSI units must be operated at a minimum of 85 percent of their maximum permitted capacity.

F. Definitions

The following definitions have been revised:

• Process change means a significant permit revision, but only with respect to those pollutant-specific emission units for which the proposed permit revision is applicable, including but not limited to:

(1) A change in the process employed at the wastewater treatment facility associated with the affected SSI unit (

e.g.,

the addition of tertiary treatment at the facility, which changes the method used for disposing of process solids and processing of the sludge prior to incineration).

(2) A change in the air pollution control devices used to comply with the emission limits for the affected SSI unit (

e.g.,

change in the sorbent used for activated carbon injection).

• Sewage sludge incineration (SSI) unit means an incineration unit combusting sewage sludge for the purpose of reducing the volume of the sewage sludge by removing combustible matter. Sewage sludge incineration unit designs include fluidized bed and multiple hearth. A SSI unit also includes, but is not limited to, the sewage sludge feed system, auxiliary fuel feed system, grate system, flue gas system, waste heat recovery equipment, if any, and bottom ash system. The SSI unit includes all ash handling systems connected to the bottom ash handling system. The combustion unit bottom ash system ends at the truck loading station or similar equipment that transfers the ash to final disposal. The SSI unit does not include air pollution control equipment or the stack.

V. Significant Public Comments and Rationale for Changes to the Proposed Rule

This section contains a brief summary of major comments and responses. EPA received many comments on this subpart covering numerous topics. EPA's responses to all comments, including those below, can be found in the comment response document for SSI units in the docket.

A. Legal and Applicability Issues Regulating SSI Under Section 112 vs. Section 129

Comment:

Many commenters contended that SSI are within the CWA definition of POTW; therefore, according to CAA section 112(e)(5), EPA must regulate SSI units under CAA section 112(d), and not CAA section 129. The commenters emphasized that SSI units are located within each respective POTW and are wholly integrated into the solids handling and treatment processes at each POTW.

Other commenters stated that SSI units cannot be regulated under CAA section 129 because they are combusting material that is generated by the POTW, which is neither a commercial or industrial establishment nor the general public as required in CAA section 129(g)(1). The commenters added that, based on the proposed definition of solid waste, even if they had a new point of generation within the POTW where they were generating solid waste, the POTW sewage sludge is from a municipal source and does not pass the broad applicability for solid waste incineration under CAA section 129. Another commenter added that CAA section 129(a)(1)(B)-(C) also directs EPA to set standards for solid waste incineration units combusting municipal waste, but to qualify as a unit combusting municipal waste, the unit must first be a solid waste incineration unit. The commenters concluded that this would not include SSI units.

Several commenters stated that EPA's determination to regulate SSI units under CAA section 129 contradicts previous decisions where EPA has stated that regulations were being developed for SSI under CAA section 112. Another commenter stated that EPA's revision to the list of source categories under CAA section 112 to delete SSI units was because there were no major sources in the source category. One commenter added that EPA's decision to regulate SSI units under CAA section 129 is based on an overly broad reading of the NRDC case. The commenter also claimed that SSI units are not within the scope of the definition of “solid waste incineration unit” in section 129 because sewage sludge is not generated by a commercial or industrial establishment or by the general public.

Response:

EPA disagrees with the commenter's assertion that regulation of SSI units under section 129 is inconsistent with past EPA statements. As explained in the NPRM, EPA issued emissions standards for POTW in 1999 pursuant to section 112(d), and those emissions standards did not include standards for SSI units. In the proposed POTW emissions standards, EPA stated that “[s]ewage sludge incineration will be regulated under section 129 of the CAA[.]”

See

63 FR 66087 (December 1,

1998). EPA also explained in the NPRM for today's action that the EPA's statements regarding SSI units during its promulgation of emissions standards for OSWI units are squarely in conflict with the Court's decision in

NRDC

EPA,

489 F.3d 1250 (D.C. Cir. 2007), which states in pertinent part that any unit that combusts any solid waste at all is subject to CAA section 129. The commenter does not appear to disagree with that conclusion, but instead simply argues that EPA cannot regulate SSI units under section 129 because it previously stated that it would regulate them under section 112. However, the NRDC decision precludes EPA from doing so. Additionally, section 112(c)(6) requires that EPA promulgate emission standards assuring that sources accounting for not less than 90 percent of the aggregate emissions of each of the HAP identified in section 112(c)(6) are subject to emission standards. EPA has determined that section 129 source categories can be included to meet our 90 percent obligations. Therefore, EPA has included SSI units in the section 112(c)(6) list of sources because SSI units are need to meet our 90 percent requirement for mercury. This decision is documented in the memorandum “Emission Standards for Meeting the Ninety Percent Requirement under Section 112(c)(6) of the Clean Air Act” in the SSI docket (EPA-HQ-OAR-2009-0559)

Moreover, section 112(e)(5) does not require EPA to issue emissions standards for SSI units under section 112(d). Rather, it simply governs the schedule for the issuance of section 112(d) emissions standards for POTW. Section 112(e), titled “Schedule for Standards and Review,” generally requires EPA to establish emissions standards for initially listed source categories as expeditiously as practicable, with certain specific deadlines in section 112(e)(1). Section 112(e) further describes how EPA shall prioritize source categories for regulation, and requires EPA to establish a schedule for issuance of emissions standards for section 112 listed source categories. Finally, Congress specified a different schedule for POTW in section 112(e)(5), stating that emissions standards shall be issued no later than November 15, 1995. Thus, section 112(e)(5) does not require EPA to regulate SSI units under section 112(d), but rather simply identifies the date by which EPA must issue emissions standards for POTW.

Additionally, the commenter's interpretation of section 112(e)(5) would conflict with section 129(g) and with the DC Circuit's interpretation of section 129(g) as explained in

NRDC

EPA.

Section 129(g) defines “solid waste incineration unit” to include any unit combusting any solid waste, and the Court in

NRDC

EPA

rejected EPA's position that it could choose to regulate certain units, combusting solid waste, under section 112 instead of under section 129. Since SSI units do combust solid waste, EPA does not have the discretion under section 129 to create an exemption for SSI units from the statutory definition of solid waste. The court noted that section 129(g) itself specifies certain units that combust solid waste but are exempt from the definition, and noted that where Congress created such enumerated exemptions, the EPA lacks discretion to create additional ones.

EPA also disagrees with the commenter that SSI units do not combust waste from the general public. Sewage sludge clearly originates from the general public, including residential and commercial facilities. Simply because the waste is treated at a POTW prior to combustion does not change the original source of the sewage sludge. The commenter refers to a statement in EPA's 2000 Unified Regulatory Agenda to support its argument. However, the Regulatory Agenda did not represent an Agency interpretation following a notice and comment process. Moreover, as explained above, EPA's position regarding the section of the Act under which SSI units must be regulated has changed since 2000, in light of the DC Circuit's decision in

NRDC

EPA.

Finally, EPA notes that its final action on reconsideration of the OSWI rule did not refer to the source of sewage sludge as a basis for concluding that regulation under section 129 was not required. Instead, as explained above, it referred to discretion the Agency believed it had at the time to choose to regulate certain solid waste incinerators under section 112—discretion the Agency no longer believes it has.

The commenter's reference to statements made in other

Federal Register

notices that pre-date the

NRDC

decision similarly fail to support its argument that EPA must regulate SSI units under section 112. Specifically, commenters refer to EPA's inclusion of SSI on the list of area source categories listed under section 112(c)(3) and (k)(3)(B)(ii) of the Act.

See

67 FR 70427 (Nov. 22, 2002). However, that listing does not lead to the conclusion that SSI must be regulated under section 112. First, as explained above, EPA's interpretation of its authority to regulate SSI has changed following the issuance of the DC Circuit's decision in

NRDC

EPA,

which occurred after the 2002 listing referred to by the commenter. Additionally, that listing included source categories that would clearly be regulated under section 129, such as medical waste incinerators and municipal waste combustors, Id. at 70428, because EPA's regulation of incinerator source categories under section 129 serves towards meeting its statutory obligations under section 112(c)(3) and (k)(3)(B)(ii). Therefore, the inclusion of SSI on that list does not indicate that such units must be regulated under section 112.

EPA further disagrees that regulation of SSI units under section 129 is unnecessary because SSI units are already regulated under section 405 of the CWA and that section 129 regulation will therefore provide no public health or environmental benefit. As explained in section VI of this preamble, today's action will benefit public health and the environment by achieving reductions of the section 129 pollutants from SSI units beyond those required by regulations issued pursuant to the CWA. Today's action must be undertaken to comply with the Clean Air Act and the court decision in

NRDC

EPA.

EPA further notes that section 405 of the CWA expressly provides that nothing in that section is intended to waive more stringent requirements of any other law. Therefore, Congress clearly did not intend for regulation of SSI units under the CWA to preclude any other regulations, including regulation under CAA section 129.

Overlap with Other Standards

Comment:

Several commenters expressed concern that other types of solid waste incineration units could be considered SSI units and subject to the SSI standards if they combust any amount of sewage sludge. Some commenters added that the definition of a SSI does not have a

de minimis

level of sewage sludge burned. Other commenters requested clarification on whether SSI units burning non-sludge industrial waste would be subject to both SSI and CISWI. Some commenters suggested that SSI units be consistent with the MWC standards and provide an exemption for co-fired combustors firing 30 percent or less by weight of sewage sludge.

Commenters suggested that the SSI standards provide exclusions for all solid waste incineration units that meet the applicability requirements of other CAA section 129 standards, including MWCs regulated under Subparts Ea, Eb, Cb, AAAA, and BBBB. The commenters noted that the CISWI standards specifically exempted MWC units and other units subject to CAA section 129 standards.

Several commenters contended that EPA should exempt incineration units subject to hazardous waste combustor regulations and/or hazardous waste management permits under the Solid Waste Disposal Act. The commenters added that CAA section 129(g)(1) states that a solid waste incineration unit does not include incinerators or other units required to have a permit under section 3005 of the SWDA. Other commenters requested EPA include an exemption for hazardous waste combustion units that are affected sources under 40 CFR part 63 subpart EEE.

Response:

Section 129 defines solid waste incineration unit to include any unit combusting any solid waste. Therefore, EPA is not setting

de minimus

levels for solid waste burned in incinerators. An incinerator located at a wastewater treatment facility designed to treat domestic sewage sludge that combusts any amount of sewage sludge is subject to the final SSI standards. We have clarified that the final standards and guidelines do not apply to sewage sludge that is not burned in a SSI located at a wastewater treatment facility designed to treat domestic sewage sludge. Sewage sludge that is not burned in a SSI located at a wastewater treatment facility designed to treat domestic sewage sludge is subject to other section 129 standards, such as the CISWI standards (40 CFR part 60, subparts CCCC and DDDD of this part), the OSWI standards (40 CFR part 60, subparts EEEE and FFFF), the MWC standards (40 CFR part 60, subparts Ea, Eb, Cb, AAAA, and BBBB of this part) or the Hazardous Waste Combustor rule (40 CFR part 63 subpart EEE).

Hazardous waste combustion units that are required to have a permit under CAA section 3005 or the Solid Waste Disposal Act are exempt from CAA section 129 standards per CAA section 129(g)(1), therefore we do not believe an exemption is needed for this rule.

Comment:

Several commenters objected to EPA issuing the proposed SSI standards prior to making determinations regarding the definition of non-hazardous solid waste.

Response:

EPA is not making determination in this rule about the definition of non-hazardous solid waste. Section 129 of the CAA states that “solid waste” shall have meaning promulgated by the Administrator under RCRA. Therefore, today's action is consistent with using the defintion of non-hazardous secondary materials promulagted RCRA rule, elsewhere in today's

Federal Register.

Comment:

Several commenters contended that sewage sludge is not a solid waste, as the CAA defines solid waste by referencing the definition of solid waste under RCRA. The commenters added that RCRA excludes sewage sludge in what is commonly referred to as the domestic sewage exclusion (DSE). The exclusion explicitly states that solid waste does not include solid or dissolved material in domestic sewage.

Response:

This comment is not relevant to EPA's establishment of emissions standards for SSI units. Rather, it is relevant to EPA's proposed Identification of Non-Hazardous Secondary Materials That Are Solid Waste rule, and is addressed in EPA's final action on that proposed rule.

B. Subcategories

Comment:

Many commenters agreed with the development of separate EG for existing MH and FB units. The commenters also requested adding the same subcategories for the NSPS. The commenters added that it was inappropriate to consider the best performing FB SSI as the best performing similar source for the MH SSI new source category. They also stated that, as proposed, the NSPS standards would discourage a POTW's ability to modify existing MH units, including modifications to improve combustion efficiency or boost steam output for electricity generation. Some commenters stated that, by using the best performing FB unit as the basis for the NSPS for MH units, EPA was effectively setting a beyond-the-floor MACT limit for SSI units without considering any criteria that the statute requires. Other commenters agreed with the decision to use the best-performing FB unit as the best similar source for the MH SSI source category.

Other commenters requested further subcategorization based on size of the SSI unit, type of sewage sludge incinerated, limited use units, and distance over which the SSI would need to transport its sludge for disposal.

Response:

We have considered the commenters' concerns and are setting separate standards for FB and MH units at new sources in the final rule. As discussed in the NPRM, there are two types of incinerators currently used to combust sewage sludge: MH and FB incinerators. The differences between the two combustor designs result in significant differences in emissions, size of the flue gas stream, ability to handle variability in the feeds, control of temperature and other process variables, auxiliary fuel use and other characteristics. To reflect the differences in their combustion mechanisms, two subcategories, FB and MH, were developed in the NPRM for new and existing SSI sources.

At proposal for the MH new source subcategory, we considered the best-performing FB incinerator to be the best-performing similar source because we were not aware of any new MH sources that have been constructed in the last 20 years, and information provided by the industry indicates that future units that will be constructed are likely to be FB incinerators.

We have re-evaluated our decision. Although few MH units have been constructed over the last 20 years, there is no technical reason that would preclude a source from constructing a MH unit. The same design differences that distinguish existing FB and MH units also apply to new units, and provide a similar basis for subcategorizing between the two types of units. Therefore, we are setting separate standards for MH units at new and reconstructed sources. Such subcategorization is appropriate based on the differences between FB and MH units described above, and will also serve to ensure that MH units do not avoid making modifications that may require them to meet standards based on FB units. We are not subcategorizing SSI units on any other basis because we do not have data to support distinguishing units based on class, type, or size. Without such information, we do not have a basis for concluding that these types of units should be placed in a different subcategory.

C. MACT Floor Analysis

Pollutant-by-Pollutant Approach

Comment:

Many commenters objected to setting the MACT floors using a pollutant by pollutant approach because none of the facilities in EPA's database can simultaneously meet all the proposed standards. One commenter stated that EPA's MACT Floor methodology is supposed to involve “review of actual emissions data with an appropriate accounting for emissions variability”. However, the commenter contended that EPA fails to follow this guidance in a practical manner in establishing MACT Floors for SSI units and that this results is unrealistically stringent limits that are not achievable for any SSI. Several commenters noted that this was especially true for the new source standards. Several commenters added that EPA's pollutant-by-pollutant basis violates the statute and its own views of the statute. One commenter stated that if EPA cannot demonstrate that the top performers can simultaneously meet all standards, EPA has improperly circumvented the

section 129 for establishing “beyond-the-floor” standards because the “floor standards would force industry-wide technological upgrades without consideration of the factors (cost and energy in particular) which Congress mandated for consideration when establishing beyond-the-floor standards.”

Many commenters specifically mentioned that EPA's pollutant-by-pollutant, lowest emission methodology for setting the CO and NO

standards is flawed because EPA did not take into account the inherent conflict in complying with two standards. The commenters noted that CO and NO

emissions are inversely proportional. The commenters explained that decreases in CO tend to elevate NO

and vice versa. The commenters added that high temperature combustion with long residence times and high oxygen concentration results in very low CO emissions, and that those same operating conditions favor high NO

emissions. The commenters added that the conditions used to minimize CO (

i.e.,

high temperature afterburners) consume more fuel and produce more CO

emissions.

One commenter noted that the SSI unit with the most advanced control technologies, and those EPA indicated were costed in the impacts analysis, would not meet the emission limits for all of the pollutants all of the time. The commenter provided an example showing that of 11 of 30 test data points from the SSI unit in EPA's database would not comply with the Cd standard, 28 of 30 data points would not comply with the Pb standard, 22 of 30 would not comply with the HCl standard, six of six data points would not comply with the PCDD/PCDF TMB or TEQ, 86 of 105 would not comply with the CO standard, and eight of 15 would not comply with the NO

standard. The commenter concluded that data variability has not been appropriately accounted for and that EPA's method of establishing the MACT floor based on the best performing unit for each pollutant is not reasonable.

Response:

We disagree with the commenters who object to setting MACT floors on a pollutant-by pollutant basis. EPA previously has explained that although CAA section 129 does not unambiguously declare that MACT floors must be established on a pollutant-by-pollutant basis, applying the requirement to set MACT floors based on what has been achieved by the best-performing sources for each of the pollutants covered by CAA section 129 is a reasonable interpretation of EPA's obligation under that provision (62 FR 48363-64).

EPA interprets the provision in CAA section 129(a)(2) to support establishing emissions standards based on the actual emissions of “the best controlled similar unit” or “best-performing 12 percent of units in the category” for each covered pollutant. Even if we were to conclude that the commenters' interpretation is equally reasonable under the statute, which we do not, the commenters' interpretation is certainly not compelled by the statute. We maintain that our interpretation is reasonable under the statute and appropriate given the problems associated with implementing the commenters' approach.

The rest of CAA section 129 requires EPA to “establish performance standards and other requirements pursuant to section [111] of this title and this section [129] for each category of solid waste incineration units.” Pursuant to CAA section 129(a)(2), those standards “shall reflect the

maximum degree of reduction

in emissions of air pollutants listed under section (a)(4)* * *.” (emphasis added). Subsection (a)(4) then states: “The performance standards promulgated under section [111] of this title and this section [129] and applicable to solid waste incineration units shall specify numerical emissions limitations for the following substances or mixtures: PM (total and fine), opacity (as appropriate), sulfur dioxide, hydrogen chloride, oxides of nitrogen, carbon monoxide, lead, Cd, mercury, and dioxins and dibenzofurans.” Thus, the statute requires EPA to set individual numeric performance standards based on the maximum degree of reduction in emissions actually achieved for each of nine listed pollutants. Based on this, EPA believes—and has long believed—the statute supports, if not requires, that MACT floors be derived for each pollutant based on the emission levels achieved for each pollutant. Moreover, although the provisions do not state whether there is to be a separate floor for each pollutant, the fact that Congress singled out these pollutants suggests that the floor level of control need not be limited by the performance of devices that only control some of these pollutants well.

Looking at the statute as a whole, EPA declared in the 1997 rulemaking for medical waste incinerators “The EPA does not agree that the MACT floors are to be based upon one overall unit” (62 FR 48364). Pointing for instance to subsection 129(a)(4), EPA explained:

This provision certainly appears to direct maximum reduction of each specified pollutant. Moreover, although the provisions do not state whether there is to be a separate floor for each pollutant, the fact that Congress singled out these pollutants suggests that the floor level of control need not be limited by the performance of devices that only control some of these pollutants well.

Id.

Since 1997, the courts have consistently repeated that EPA must set emission standards based on the best-performing source for each pollutant.

See, e.g., Cement Kiln,

255 F.3d 855, 858 (DC Cir.) (“[T]he Agency first sets emission floors for each pollutant and source category * * *.”). Accordingly, EPA's pollutant-by-pollutant approach has, as outlined above, been in place since 1997 for medical waste incinerators, and even earlier for other types of incinerators regulated under section 129.

See, e.g.,

59 FR 48198 (September 20, 1994) (municipal waste combustors). In addition, such an approach has been upheld in other contexts.

See, e.g., Chemical Mfrs. Ass'n

EPA,

870 F.2d 177, 239 (5th Cir. 1989) (concluding that basing CWA best available technology standards on a pollutant-by-pollutant basis was a rational interpretation of EPA's obligations under that similar statute). We note that the CAA MACT provisions were fashioned on that CWA program. S. Rep. No. 228, 101st Cong. 2d sess. 133-34.

Further, utilizing the single-unit theory would likely result in EPA setting the standards at levels that could, for some pollutants, actually be based on emissions limitations achieved by the worst-performing unit, rather than the

best

-performing unit, as required by the statute. See 61 FR 173687 (April 19, 1996); 62 FR 48363-64 (September 15, 1997). For example, if the best performing 12 percent of facilities for metals did not control CDD/CDF as well as a different 12 percent of facilities, the floor for PCDD/PCDF and metals would end up not reflecting best performance. Moreover, a single-unit approach would require EPA to make value judgments as to which pollutant reductions are most critical in working to identify the single unit that reduces emissions of the nine pollutants on an overall best-performing basis. Such value judgments are antithetical to the command of the statute at the MACT floor stage. It would essentially require EPA to prioritize the nine pollutants based on the relative risk to human health of each pollutant, a criterion that has no place in the establishment of MACT floors.

Sierra Club

EPA (Copper Smelters),

353 F.3d 976, 979-80 (DC Cir. 2004).

The fact that the statute does not contain the phrase “for each pollutant” does not compel any inference that Congress was

sub silentio

mandating a different result when it left the provision ambiguous on this issue. The argument that MACT floors set pollutant-by-pollutant are based on the performance of a hypothetical facility, so that the limitations are not based on those achieved in practice, just re-begs the question of whether CAA section 129(a)(2) refers to whole facilities or individual pollutants. All of the emission limitations in this rule reflect actual performance and are achieved in practice.

An interpretation that the floor level of control must be limited by the performance of devices that only control some of these pollutants effectively “guts the standards” by including worse performers in the averaging process, whereas EPA's interpretation promotes the evident Congressional objective of having the floor reflect the average performance of best performing sources. Since Congress has not spoken to the precise question at issue, and EPA's interpretation effectuates statutory goals and policies in a reasonable manner, its interpretation must be upheld. See

Chevron

NRDC,

467 U.S. 837 (1984).

Commenters made much of the fact that no single facility is presently achieving all of the nine pollutant limits proposed. However, the available information compared to the final standards disputes this assertion. For the final standards, based on the data we have, our estimate of baseline emissions, and the revised emission limits, we are estimating that 155 of 204 existing SSI units can meet standards for all nine pollutants, without installing additional pollution control. We cannot make this assessment for new sources, because none have been constructed. However, we are not aware of any technical reason that new units could not install the most advanced pollution control techniques or reduce the pollutant concentrations in the sludge to meet the new source standards.

We recognize that the pollutant-by-pollutant approach for determining the MACT floor can, as it does in this case, increase the overall cost of the regulation compared to what would result under a unit-based methodology. We interpret CAA section 129 to require that the MACT floor be determined in this manner, and we believe that Congress did, in fact, intend that sources subject to regulations developed under CAA section 129 meet emissions limits that are achieved by the best controlled unit for each pollutant, as long as the control systems are compatible with each other. To our knowledge, there is no technical reason why these air pollution control systems cannot be combined.

Regarding the inverse relationship between CO and NO

with regard to combustion control, it is incumbent upon the SSI facility to determine whether combustion conditions can be adjusted to meet both standards and, if not, install NO

controls as necessary (

e.g.,

SNCR systems, SCR systems, FGR, or low NO

burners). In the proposed rule, we conjectured reasons why SCR and SNCR were not used or may not be able to be used at SSI units. While we are not aware of any SSI unit that currently uses SNCR or SCR, we also do not know of technical reason why they could not be used. Given the limited data available on SSI units with FGR, we could not definitely determine how effective the technology was on SSI units. However, we also do not know of a technical reason why they could not be used, if necessary, to meet NO

limits, and commenters did not provide any reasons they could not be used.

Dataset for the MACT Floor Analysis

Comment:

Many commenters urged EPA to collect more information to set the standards. Many commenters contended that EPA does not have sufficient actual emission data from enough SSI units to properly set the MACT floor. Some commenters contended that the floor-setting provision in section 129 requires them to set the existing floor standards “based on the best performing 12 percent of sources in the category” and not just based on the sources for which they have information. The commenters contended that EPA did not have emissions data from the best-performing 12 percent of sources or even from 12 percent of sources. Additionally, the commenters stated that there is no evidence that the sources for which EPA collected data are among the top 12%. One commenter added that EPA is using actual data from as little as 4.3 percent of a subcategory (7 of 163 MH units for HCl) to determine how the top 12 percent perform.

Some commenters contended that EPA chose to limit its ICR to just nine entities because collecting information from ten or more entities would have triggered the PRA obligations and a more rigorous OMB review. The commenters concluded that EPA's plan to circumvent the PRA and OMB review resulted in an inadequate dataset for this rulemaking that leaves EPA unable to reliably take the first necessary step in a section 129 rulemaking: To determine which of the SSI units are the best performing sources.

Some commenters also contended that EPA targeted its ICR to the nine POTW expected to have the lowest emissions based on the type of unit and the installed air pollution controls. The commenters contended that EPA's targeted approach to collecting data from expected top performers undermines its ability to presume the data is a random sample representative of the entire source category or subcategory. The commenters stated that if the data gathered are not representative at the outset, then the data cannot reliably be used in a statistical equation to predict the emissions data across the source category or subcategory.

Some commenters noted that in the past, EPA has used permit or other regulatory limits, emission levels, feed rate control, and other information to establish MACT standards. Despite this flexibility, the commenters stated that EPA is proposing to use an “actual emissions” method in the SSI rule, even though it does not have actual emissions for each of the regulated pollutants from at least 12% of the units.

Another commenter stated that EPA used emission data from state databases for an additional nine MHs. The commenter stated that EPA was instructed by the Court to collect data from the best-performing 12% of existing sources, and EPA needs to justify that the emissions data from the state databases for the additional nine MHs were the 12% best performing MHs.

Response:

As explained in the preamble to the proposed rule, EPA requested several SSI to conduct emissions testing and provide the results to EPA for purposes of this rulemaking. Specifically, EPA collected information on the best-performing sources to establish MACT floor standards for SSI. Therefore, EPA sent emissions tests requests under section 114 of the CAA to nine entities that own and operate SSI units. EPA identified SSI units that were expected to be the best-controlled sources and the best performers for further emissions testing. The Agency acknowledges that this selection methodology targets identifying the best-performing sources rather than selecting a representative sample of sources. However, given the court-ordered deadline for EPA to issue the final SSI rule, it was not possible to undertake the time-consuming process of sending an ICR to all the affected SSI units consistent with the requirements of the PRA.

To select the surveyed owners, EPA reviewed the inventory of SSI units for the control devices being operated, and identified a subset of units expected to have the lowest emissions based on the type of unit and the installed air pollution controls. These controls generally achieve the most reductions possible for the CAA section 129 pollutants, and thereby allow EPA to identify for each pollutant the units with the lowest emissions. For example, units were selected that operated more than one of the following technologies: Activated carbon injection to reduce Hg and dioxins/furans; RTOs or afterburners to reduce CO and organics; wet ESP to reduce fine particulate; high efficiency scrubbers such as packed bed scrubbers and impingement tray scrubbers to reduce PM, Cd, Pb, particulate Hg, and acid gases such as HCl and SO

; and units with multiple control devices that could reduce PM, Cd, Pb, particulate Hg, such as venturi scrubber in combination with impingement scrubbers and wet ESPs or with another particulate control device. The 9 owners or operators selected were from different states in different regions of the country, providing a wide spectrum of sources for sludge generated.

Six of the nine ICR recipients operate MH units, resulting in 13 MH units surveyed. Three of the nine operate FB units, resulting in 7 FB units surveyed. Some owners of multiple units at a facility provided information for less than the total number they operated,

e.g.

1 unit instead of 2, because not all units were in operation during the test period. Of those 20 units from the nine surveyed municipalities, EPA collected data from 17 units that were in operation (11 MH units and 6 FB units). While testing was being undertaken, the EPA also collected emission test information for 9 MH SSI units collected from state environmental agencies public databases. For some pollutants, the emissions from these supplemental test reports were lower than those from the nine ICR sources. The EPA concluded that it was appropriate to use all the emissions information from these test reports in the MACT floor analysis. The EPA also collected many test reports that were older than 15 years. The older reports were determined to not be appropriate for this rulemaking because they were unlikely to represent current emissions performance, due to their age and because they pre-dated required compliance with the CWA part 503 standard. In total, emissions information were collected from 6 FB units and 20 MH units from facilities responding to the ICR and additional test reports provided by state environmental agencies.

As discussed in the NPRM and background documentation, the EPA conducted a statistical analysis to verify the minimum number of observations needed to accurately characterize the distribution of the best-performing 12 percent of units in each subcategory. The results showed that the data utilized by EPA meets or exceeds the number of observations necessary to provide an accurate representation of that data distributed from the best-performing 12 percent of the source population. The EPA maintains that the emissions information that we have collected is adequate to determine the MACT floor for the best-performing sources. The EPA disagrees with the commenters' recommendation to use other types of data, such as permits, other regulatory limits, or feed rate controls with the emissions information to calculate the MACT floor. The other types of data mentioned do not represent the actual emissions or operation of the unit but are potential values in their permits or limits. Most units are typically operating at lower than permitted levels or emission limits.

Additionally, it would be difficult to incorporate such data into the EPA's UPL calculation because the UPL calculation is based on emission test runs of actual data, rather than limits based on permits. The permit or emission limits would be on a different basis and potentially skew the MACT floor UPL calculation.

The EPA has also updated the inventory of sources based on additional data provided in the comment letters. The inventory now contains 204 SSI units, 60 FB units and 144 MH units. Given this change in population, 12 percent of each subcategory are equal to 8 FB units and 18 MH units. Although we do not have any more emissions information than at proposal, the change in inventory results in more than 12 percent of MH units with data for PM and Hg. For these pollutants, we determined the MACT floor based on the best-performing 12 percent of emissions data, as documented in the memorandum “Revised MACT Floor Analysis for the Sewage Sludge Incinerator Source Category” in the SSI docket (EPA-HQ-OAR-2009-0559). EPA solicited additional emission test reports in the NPRM. Although many commenters summarized the results of their most recent emission tests when comparing their site-specific emissions to EPA's baseline emissions, none of the commenters actually provided the emissions test reports. The emission test reports are necessary for the EPA to review the test methods and procedures to ensure consistency with other emissions data, and to verify the tests represent a valid test result that can be used in the MACT floor analysis. Additionally, the test reports provide information necessary to correct the emissions measured into the units used for the MACT floor analysis. Therefore, these additional test result summaries, without background documentation, could not be used in the MACT floor UPL calculation.

Comment:

One commenter stated that, to fill the data gap caused by the lack of actual emissions data from the required number of units in each subcategory, EPA applied statistical analysis to single test run results. Several commenters contended that, in order to enhance the data available for MACT development, EPA counted each test run as a separate data point.

Some commenters stated that basing a MACT Analysis on test runs, instead of tests, is improper. The commenters noted that CAA section 129 states that MACT standards for existing sources must be as stringent as the “emissions limitation achieved by the best performing 12 percent of units in, the category.” The commenters added that, assuming that EPA equates the term “emissions limitation” with the concept of emission level (as often stated by EPA), this clause means that EPA must use the emission levels that have been achieved to set the MACT floors. The commenters contended that, under the MACT program, it takes a “minimum” of three test runs to make up a valid emissions level test. The commenter stated that a test run is not an accurate measure of the performance of the unit and should not be used as if it were. Commenters added that EPA should use the results of the test for each unit (comprised of at least three test runs) to represent what is being achieved by a unit.

Several commenters contended that EPA must go back and reset the process based on 12% of MH and 12% of FBI sources (not individual incinerators). The commenters added that it is important that individual sources, not units, be utilized because the composition of the sludge varies greatly from source to source and utilizing multiple units at one source skews the data development process and ultimately provides the basis for a flawed MACT standard at best.

Response:

We disagree with the commenters. The 99 percent UPL values were calculated for each pollutant and for each subcategory using the test run

data for those units in the best-performing 12 percent. Consistent with EPA's procedures on other MACT standards, such as HMIWI, CISWI, and boilers, the MACT floor emission limits were calculated on a run basis since compliance is based on the average of a 3-run test. The 99 percent UPL represents the value which one can expect the mean of future 3-run performance tests form the best-performing 12 percent of sources to fall below, with 99 percent confidence, based upon the results of the independent sample observations from the same best-performing sources.

Variability Calculation

For the final rule, as in the NPRM, we are incorporating variability in the MACT floor calculation for this source category using the 99 percent UPL. We are also following the same procedures for establishing limits and incorporating non-detect values as discussed in the NPRM. We have made three revisions to the variability calculation for the final rule. First, we revised the MACT floor variability calculation to incorporate weighted UPL's for existing FB units. Second, we selected log-normal results when it is not clear that data are normally distributed. Lastly, we revised the CO limits based on an analysis of the span of the test. The weighted UPL's and log-normal results are discussed in responses to comments. The revision to the CO limits based on reviewing the CO span was done to correct errors in the CO values provided in test reports and to be consistent with the calculation methods used in the CISWI and boilers rules.

Carbon monoxide values obtained from emission test reports were reviewed to determine whether the span of the test used was capable of accurately reading the reported value. If the span was inconsistent with the reported value, the CO levels were adjusted to provide a value that was more consistent with the span. EPA Method 10 is structured such that measurement data quality relative to the calibration span of the instrument can be assessed. For a measurement made using an instrumental test method, the equivalent of the method detection level can be assessed using: a square root formula, the reported calibration span value, and the allowable data quality criteria (

i.e.

the allowable calibration error, bias, and drift values). The estimated CO measurement error resulting from the square root formula was adjusted by a factor of three to be consistent with the methodology EPA applied for non-detect data (where limits no less than three times the method detection level were established).

In order to develop a basis for measurement error, instrument calibration spans in available test reports were reviewed. Where no span values could be found, it was assumed that if the test was conducted on or before May, 2008, the associated CO span would be 1000 ppm, and tests conducted after May 2008 would have a CO span of 100 ppm. This assumption was made because, before revisions were made to Method 10 in May of 2008, it was common that units were using the prescriptive span guidance that was listed in the old method. The current version of EPA Method 10 does not include these span requirements but instead requires the tester to choose calibration ranges that reflect the range of expected emission concentrations at the unit. In cases where the reported emission concentrations were lower than their corresponding measurement errors, the default measurement errors were used in lieu of the reported concentration.

These revisions are further documented in the memorandum “Revised MACT Floor Analysis for the Sewage Sludge Incinerator Source Category” in the SSI docket (EPA-HQ-OAR-2009-0559). Table 7 of this preamble shows the revised results of the MACT floor analysis for existing sources, and Table 8 of this preamble shows the results for new sources.

Table 7—Summary of MACT Floor Analysis for Existing SSI Units

Pollutant

Units

MACT floor emission limit

for FB

incinerators

MACT floor emission limit

for MH

incinerators

mg/dscm@7% O

0.0016

0.095

ppmvd@7% O

3,800

HCl

ppmvd@7% O

0.51

1.2

mg/dscm@7% O

0.037

0.28

ppmvd@7% O

150

220

mg/dscm@7% O

0.0074

0.30

PCDD/PCDF TEQ

ng/dscm@7% O

0.1

0.32

PCDD/PCDF TMB

ng/dscm@7% O

1.2

5.0

mg/dscm@7% O

ppmvd@7% O

Limits were rounded up to two significant figures.

Limits represent three times the detection level.

Table 8—Summary of MACT Floor Analysis for New SSI Units

Pollutant

Units

MACT floor emission limit

for FB

incinerators

MACT floor emission limit

for MH

incinerators

mg/dscm@7% O

0.0011

0.0024

ppmvd@7% O

HCl

ppmvd@7% O

0.24

1.2

mg/dscm@7% O

0.0010

0.15

ppmvd@7% O

210

mg/dscm@7% O

0.00062

0.0035

CDD/CDF TEQ

ng/dscm@7% O

0.0044

0.0022

CDD/CDF TMB

ng/dscm@7% O

0.013

0.045

mg/dscm@7% O

9.6

ppmvd@7% O

5.3

Limits were rounded up to two significant figures.

Limits represent three times the detection level.

Limits defaulted to EG limits since NSPS limits were less stringent than EG.

Comment:

One commenter contended that because CAA section 129 unambiguously requires EPA to set floors reflecting the “average” emission level achieved by the best sources, setting floors that instead reflect a UPL for those sources is unlawful. The commenter, added that by claiming that it can use the UPL for all sources in the top twelve percent, EPA misreads its authority to consider variability under the CAA and relevant case law. The commenter explained that, although EPA may consider variability in estimating an individual source's actual performance over time, nothing in the CAA or the case law even suggests that EPA may account for differences in performance between sources except as section 129 provides, by averaging the emission levels achieved by the sources in the top twelve percent.

Response:

In assessing sources' performance, EPA may consider variability both in identifying which performers are “best” and in assessing their level of performance.

Sierra Club

EPA (Brick MACT),

479 F. 3d 875, 881-82 (D.C. Cir. 2007); see also

Mossville Environmental Action Now

EPA,

370 F.3d 1232, 1241-42 (D.C. Cir 2004) (EPA must exercise its judgment, based on an evaluation of the relevant factors and available data, to determine the level of emissions control that has been achieved by the best performing sources considering these sources' operating variability). The

Brick MACT

decision indicated that floors for existing sources must reflect the average emission limitation achieved by the best-performing 12 percent of existing sources. The

Brick MACT

decision also reiterated that EPA may account for variability in setting floors; however, the Court found that EPA erred in assessing variability because it relied on data from the worst performers to estimate best performers' variability. The Court held that “EPA may not use emission levels of the worst performers to estimate variability of the best performers without a demonstrated relationship between the two.” 479 F. 3d at 882.

In determining the MACT floor limits, we first determine the floor, which, for existing sources, is the emissions limitation achieved in practice by the average of the top 12 percent of existing sources, or the level achieved in practice by the best controlled similar source for new sources. In this rule, EPA is using lowest emissions limitation as the measure of best performance. We then assess variability of the best performers by using a statistical formula designed to estimate a MACT floor level based on the average of the best performing sources using the expected distribution of future compliance tests. We used the UPL to perform this calculation, as explained below.

Variability can be accounted for using different statistical methods. For example, recent standards have used the UL or the UPL to determine the MACT floor emission limits. A UL is based on the distribution of the available emission observations (

e.g.,

test runs), and does not embody a predictive aspect that a UPL does. A prediction interval (

e.g.,

a UPL) for a future observation is an interval that will, with a specified degree of confidence, contain the next (or some other pre-specified) randomly selected observation from a population. In other words, the prediction interval estimates what future values will be, based on present or past background samples taken. Given this definition, the UPL represents the value the mean of three future test run observations (three-run average) can be expected to fall below, based on the results of the independent sample of size (n) from the same population. Therefore, should a future test condition be selected randomly from any of these sources (

i.e.,

average of three runs), we can be 99 percent confident that the reported level will fall below a MACT floor emission limit calculated using a UPL. The UPL is an appropriate statistical tool to use in determining variability in the SSI data. For this source category, where there is a limited sampling of the source category and we do not have test data from all of the SSI units in the best performing 12% for each subcategory, the predictive aspect of the UPL calculation is especially important.

Because the UPL represents the value which we can expect the mean (

i.e.,

average) of three future observations (3-run average) to fall below, based upon the results of the independent sample size from the same population, the UPL reflects average emissions. The UPL is also consistent with other recent rulemakings.

Comment:

Several commenters asserted that, in setting MACT standards for existing units, EPA pooled and utilized data from all available test runs for the best performing units without regard to the number of data points available for each unit. The commenters added that, for all pollutants, the number of test runs varies from unit to unit. One commenter stated that using data this way biases the statistical results, and ultimately, the standards by over-weighting the performance of the units that have more data. The commenter suggested that EPA should employ an alternate methodology which determines the emissions limitation achieved for each best performing unit first, and then averages these limitations to determine the least stringent standard, or MACT floor.

Response:

The SSI emissions database for fluidized bed units contains data from six units at four facilities. The entities surveyed were requested to provide recent (within the previous 5 years) emissions test reports. Most survey recipients provided only the most recent report. One facility, with three units, provided results of emissions test conducted for compliance reports spanning a 10-year period. This facility also uses the most advanced pollution controls on their fluidized bed units in the subcategory. This facility constitutes 70 percent of the Cd and Pb data, 90 percent of the CO and Hg data, and 75 percent of the HCl data and PM data. As a result, the existing source MACT floors calculated using the UPL methodology, and all the test run data from the one facility, effectively result in calculating more stringent limits more akin to a new source MACT floor than an existing

source MACT floor, because it is based primarily on only the emissions performance of the best-performing single source, rather than the average of the best-performing 12 percent of sources. In order to adequately incorporate the emissions from the best-performing SSI units in the fluidized bed subcategory, a weighted UPL was used for calculating the existing source MACT floors for the final rule. The weighted UPL is calculated from a weighted mean and weighted variance as described below.

There are many different types of weighting procedures. We have chosen the most straightforward methodology, to base it on the number of data points (

i.e.,

test runs) from each SSI unit.

This weighting scheme ensures that no facility in the MACT best performers pool is over-represented in the computation of the MACT floor. The first step in weighting procedure is to assign a weighting factor to each test run by multiplying each observation for source

and run

with a weight term, w

, as shown in Equation 1 of this preamble:

Heckert, N. A. and Filliben, James J.(2003). “NIST Handbook 148: DATAPLOT Reference Manual, Volume I: Commands”, National Institute of Standards and Technology Handbook Series, June 2003. [Available at

http://www.itl.nist.gov/div898/software/dataplot/document.html

]

ER21MR11.014

Where:

= Number of observations (

i.e.,

runs) for source i and

= Number of best performing sources in the MACT pool.

The second step is to calculate the mean and total variance for the weighted data from the weight terms using Equations 2 and 3 of this preamble:

ER21MR11.015

ER21MR11.016

Where:

ER21MR11.017

is the total number of observations in the MACT best performers pool.

When the weights are equal to one, the above equations reduce to those for un-weighted data, as expected. As shown in Equation 4 of this preamble, the weighted mean and weighted variance are then used in the UPL calculation (discussed in the NPRM) instead of the simple (

i.e.,

un-weighted) mean and variance.

ER21MR11.018

For multiple hearth units, there are more emissions data from a larger number of facilities/units. For example, we have data on Cd and Pb from 11 facilities with 14 units, Hg from 11 facilities with 18 units. The MACT floor calculations are not skewed by one or two units or facilities. Consequently, the MACT floor for existing multiple hearth units does not need to be calculated using a weighted UPL.

The revisions to the MACT floor methodology are discussed in detail in the memorandum “Revised MACT Floor Analysis for the Sewage Sludge Incinerator Source Category” in the SSI docket (EPA-HQ-OAR-2009-0559).

Comment:

One commenter contended that EPA should determine the MACT floor emission limits to be consistent with EPA's Guidance for Data Quality Assessment Manual, which holds that it is more likely that environmental data are distributed log-normally. The commenter considered it reasonable to believe that environmental emission distributions are non-normal, since frequency plots typically show many readings approaching zero and fewer large readings forming an elongated tail to the right. The commenter concluded that normal distributions may exist for certain pollutants where the entire dataset is many standard deviations away from zero, and values are controlled by an air pollution control process with set points and feedback and control loops.

Response:

We have reviewed the document referenced and agree with the commenter that the referenced document shows that environmental data are more likely to be log-normally distributed than normally distributed. In the proposed rule, two statistical measures, skewness and kurtosis, were examined to determine if the data used

to calculate the MACT floor were normally or log-normally distributed. If both the reported values and the natural-log transformed reported values had skewness and kurtosis statistics that indicated neither were normally distributed, the reported dataset was selected as the basis of the floor to be conservative. If the results of the skewness and kurtosis hypothesis tests were mixed for the reported values and the natural log-transformed reported values, the analysis done on the reported data values was chosen to be conservative.

Based on “Guidance for Data Quality Assessment: Practical Methods for Data Analysis” EPA/600/R-96/084, July 2000, we have modified our assumptions when results of the skewness and kurtosis tests do not clearly show whether a normal or log-normal distribution better represents the data, or when there are not enough data to complete the skewness and kurtosis tests. In these cases, we have chosen to use the log-normal results for the final MACT floor calculation.

Comment:

Some commenters contended that EPA incorrectly presumes that stack test results account for the full variability of a SSI's performance. Several commenters stated that emissions from SSI units are affected not just by control technology but also by other factors including the contents of the sludge that a unit is burning. Many commenters urged EPA to determine the MACT floor limits by incorporating the variability of the sludge contents. The commenters added that the methodology in developing the proposed standards does not take into account that Hg, Cd, Pb, HC1 and SO

emissions are a function of the sludge content of Hg, Cd, Pb, chlorine and sulfur. The commenters expressed concern that the limits were based on test results obtained with sludge containing very low concentration of metals, chlorides, and sulfur. The commenter explained that if the sludge burned during an emissions test was not at or near the maximum constituent concentration level (

e.g.,

due to seasonal variability), a new source emission limit based on these data could not be achieved over the full range of expected normal operating conditions confronted by the best performing source.

The commenters contended that EPA must consider all available data (including Part 503 data) for the best performing source and use that to establish a variability factor applied to the stack test data. The commenters added that EPA's request for metals data during the stack test is insufficient to account for the full intra-source variability. The commenters added that variability for the compounds not regulated by Part 503 must also be accounted for as well before setting the new source limit.

The commenters explained that POTW, and their SSI units, are statutorily obligated to manage all of the sewage that enters into the sanitary sewer system, resulting in highly variable and often unpredictable spikes in concentrations. The commenters continued that POTW inlet concentrations also vary based on the nature and type of dischargers. The commenters explained that POTW treat wastewater from residential, commercial and industrial dischargers in varying degrees, and pretreatment opportunities also vary because POTW authority to control discharges into the sewer system is limited and the way that authority is exercised varies. The commenters also noted that the nature of sewage entering the POTW changes over time as the character of a community changes, the age of the population changes, and commercial and industrial dischargers come and go. The commenters added that without the use of long-term data to support the level of emission standards, this variability makes numeric technology-based limits impractical and infeasible. The commenters also explained that POTW also face significant regional and seasonal variability that is not captured by EPA's dataset. The commenters stated that initial high flow periods in the spring often scour the sewers and dislodge heavier material that has settled in the sewer system during low-flow periods, which often results in a spike in metals concentrations (

e.g.,

Hg, Cd, Pb) in the sewage sludge. The commenters noted that the ICR stack tests in January and February that were used for the EPA database would not have captured these events. The commenter also noted that northern cities that use salt for de-icing roadways experience significant increases in chlorides during the winter months, and high chloride concentrations are known to improve the effectiveness of Hg control at existing wet scrubbers.

Response:

The variability analysis is based on emissions information gathered from nine different facilities located in nine different states. The facilities we collected emissions information from are located in a mix of northern, southern, eastern, and western states. Each facility has its own unique sludge characteristics from different residential and commercial populations. We agree that the emissions data represents a “point in time”. However, combined together, they represent sufficient variation in regions, climates and populations that adequately incorporates variability in wastewater treatment systems across the U.S. We have also incorporated variability using the UPL. The variability analysis based on the emissions data collected adequately characterizes the potential differences in sludge contents and regional differences. Because we have a mixture of southern and northern states in the emissions database, we believe that it also adequately considers differences between cold and warm weather climates. Additionally, we did not have sufficient information at proposal to consider if it were appropriate to incorporate variability based on sludge content. We requested additional information in the NPRM, but did not receive adequate sampling data from the best-performing sources.

Comment:

Some commenters claimed that EPA's identification of the relevant best performing units for both existing and new unit standards is both unlawful and arbitrary, and EPA may not use sources' control technology as a proxy for their actual performance unless “pollution control technology is the only factor determining emission levels.”

Cement Kiln Recycling Coalition

EPA,

255 F.3d 855. 863 (DC Cir. 2001). The commenters stated that, in

Cement Kiln Recycling Coalition

EPA,

255 F.3d 855 (DC Cir 2001) (“CKRC”), the Court considered Sierra Club's challenge that EPA could not set the floors based solely on the performance of one method: Add-on technology. The commenters added that the Court remanded the rule because EPA did not consider all of the ways facilities control emissions. The commenters stated that this requirement is consistent with doing a more complete study as required by section 111 and is antithetical to a methodology based solely on emission levels since setting the floor in this fashion does not require EPA to examine all methods of control. The commenters concluded that EPA's performance data approach in this rule may violate CKRC because EPA did not check for all methods that sources use to reduce pollution.

Response:

EPA disagrees with the commenter who alleges that EPA has not properly identified the best performing SSI units for purposes of calculating MACT floor limits. As explained above, EPA targeted its emissions testing requests to units it believed had the lowest emissions, while accounting for factors such as sludge content and seasonal variation by selecting units in different geographic areas of the country.

EPA further notes that SSI units currently employ non-technology measures (pollution prevention) to reduce emissions to comply with CWA regulations at 40 CFR part 503. These regulations establish daily average concentration limits for Pb, Cd, and other metals in sewage sludge that is disposed of by incineration. Part 503 also requires that SSI meet the National Emission Standards for Beryllium and Hg in subparts C and E, respectively, of 40 CFR part 61. In order to meet the 40 CFR part 503 standards, facilities are already incorporating management practices and measures to reduce waste and limit the concentration of pollutants in the sludge sent to SSI units, such as segregating contaminated and uncontaminated wastes and establishing discharge limits or pre-treatment standards for non-domestic users discharging wastewater to POTW. Thus, the facilities from which EPA received emissions test results are already applying non-technology measures to reduce emissions.

Comment:

One commenter suggested that if EPA employs the statistical limit to set MACT floor emission limits, it should use the 99.9 percent limit. The commenter stated that the 99.9 percent UPL represents a 0.1 percent probability of a failure for individual tests, or a one percent per unit non-compliance probability per annual performance test program. The commenter concluded that this value better encompasses unit emissions variability and represents a manageable risk to the responsible facility operator.

Response:

We disagree with the commenters. For the final standards, we maintain the use of 99 percent UPL is appropriate and sufficiently addresses variability in the emissions information. Our analysis of variability is explained in detail in the memorandum “Revised MACT Floor Analysis for the Sewage Sludge Incinerator Source Category” in the SSI docket (EPA-HQ-OAR-2009-0559).

Comment:

Several commenters opposed an opacity limit of zero percent because opacity is a subjective measurement and no unit can meet opacity limits of zero at all times. Another commenter suggested that control and monitoring of PM is sufficient.

Response:

We agree that a no visible emissions (zero opacity) limit for combustion processes is impractical for both compliance and enforcement purposes. We also believe that a measurable opacity may or may not be indicative of compliance with a PM emissions limit when applied to multiple sources within the category. That is, an opacity limit applied to one facility could very readily correspond to a PM emissions level different than that same opacity limit applied to another facility and one or both may be emitting above the PM limit. That opacity limits do not apply very well when wet control devices are used further confounds the benefit of such regulatory limits. We also agree that there are both CEMS and site-specific parametric monitoring approaches applicable to various control devices that can be more closely aligned with PM control and compliance with the PM emissions limit than would an opacity limit and opacity monitoring. Instead of establishing opacity limits that may or may not assure compliance with PM emissions limits, the final rules include rigorous requirements for establishing site-specific operating limits derived from the results of performance testing. The rules also include a requirement that sources update those enforceable operating limits with each repeated performance test. Re-establishing operating limits periodically will assure that the monitoring will continue to indicate compliance with the PM emissions limits. The rules also provide the source the option of apply CEMS to monitor directly the pollutant of interest in lieu of parametric monitoring. We believe that continuous compliance with operating limits and periodic stack testing to verify the operating limits plus the CEMS option will ensure that sources demonstrate continuous compliance with the PM emission limits more effectively than would periodic or continuous monitoring of a broadly applicable opacity limit.

Format of the Standards

Comment:

Several commenters requested that EPA develop emission limits for some pollutants in different units or to provide a control efficiency alternative. The commenters expressed concern that the use of concentration limits would not reflect the variability of the unique sludge characteristics of each SSI unit, and may unfairly penalize units with very low or very high feed concentrations of certain pollutants, such as Hg, Cd, or Pb. Some commenters suggested establishing limits similar to the EPA 503 regulations, which provided emission limits based on control efficiencies coupled with feed concentration limits.

Response:

We did not have sufficient data to set alternative control efficiency standards or standards in other units at proposal. We requested additional information in the proposal. However, sufficient data were not provided in response to our request for alternative formats to be developed.

D. Baseline Emissions

Comment:

Commenters stated that EPA overestimated baseline emissions because EPA used incorrect air flow rate parameters, pollution control device efficiencies, sludge feed rates, and operating hours. Many commenters provided stack test data, emission estimates, and corrections to the EPA's SSI inventory database. Other commenters noted that EPA used uncorrected flue gas flow rates and flow rate factors in combination with pollutant concentrations corrected to seven percent oxygen.

Response:

We have incorporated corrections to the inventory and calculation inputs provided by the commenters where applicable. In some cases, commenters did not provide information sufficient for us to revise the inventory or calculation inputs for the commenter's facility. For example, commenters may have provided an average concentration for a pollutant, but did not provide run-specific information that would allow us to convert the concentration information provided to standardized units (7 percent oxygen). Other commenters may have provided emission rates in pounds per hour, but did not provide vent gas flow rate, oxygen content, or moisture content to convert to concentration units. None of the commenters provided test reports that would have include this information.

We have also revised the calculation of baseline emissions by revising the defaults assigned to SSI units where information was not available. Defaults were necessary to be assigned because, even after new data were received in comments, a significant number of units did not have data on sludge capacity, flue gas flow rates,

etc.

A detailed discussion of the methodology used to estimate baseline emissions for the final standards is presented in the memorandum “Revised Estimation of Baseline Emissions from Existing Sewage Sludge Incineration Units”(EPA-HQ-OAR-2009-0559). The revisions to the inventory and other corrections resulted in the final rule baseline emissions shown in Table 9 of this preamble. The table shows a range of emissions for each pollutant. The lower bound represents an estimation of actual emissions based on the actual dry sludge feed rates commenters indicated their units were running. The upper bound represents an estimation of potential emissions if the sludge feed rate was at the dry sludge capacity of each unit. We estimated the potential

emissions because the amount of wastewater treated (and sludge produced) may vary significantly based on changes in population or sources of wastewater. Facilities have the potential to burn up to their units permitted capacity although they may not be doing so currently.

Table 9—Estimated Baseline Emissions for Existing SSI Units

Pollutant

Range of baseline emissions by

subcategory (TPY)

Range of total baseline

emissions (TPY)

0.0022-0.0015

0.91-1.2

73-100

8,400-11,500

8,500-11,600

HCl

1.6-2.2

26-41

28-43

0.040-0.058

0.85-1.15

0.9-1.2

320-480

2,100-2,800

2,400-3,300

0.0056-0.0077

2.4-3.1

PCDD/PCDF TEQ

0.00012-0.00016

0.00076-0.0010

0.0009-0.0012

PCDD/PCDF TMB

0.0014-0.0020

0.011-0.015

0.013-0.017

25-37

310-410

330-450

43-57

660-1,020

700-1,100

Baseline emissions are in pounds per year for PCDD/PCDF.

E. Beyond-the-Floor Analysis

Comment:

Several commenters requested that EPA reconsider the beyond-the-floor Hg limit for MH units because baseline Hg emissions were overstated and costs for Hg control were understated. Many of the commenters contended that carbon injection is an unproven technology for SSI units, and is currently used at only one facility with FB units. The commenters added that the facility is undergoing significant issues with the technology.

Commenters also contended that Hg removal using carbon injection cannot be accomplished with existing PM controls, such as venturi scrubbers, and that FFs would be necessary. The commenters added that the high moisture content in the form of liquid droplets from the incinerator will plug FFs, and additional equipment may be necessary to keep the temperature above the dew point, such as an afterburner.

Response:

We have revised the beyond-the-floor analysis to incorporate changes made to the baseline emissions, new facility specific data and inputs provided by commenters, and revised control options. We analyzed several beyond-the-floor controls for the final rule. First, we evaluated the use of an afterburner for control of CO at MH units. We then evaluated whether additional control of Hg should be required at MH units. We have reviewed the commenters concerns regarding Hg control technologies and agree that applying carbon injection to existing scrubbers has not been demonstrated to be effective at removing Hg. For combustion sources that are not SSI, such as boilers, carbon injection in combination with a FF has proven to be highly effective in removing Hg. However, for high moisture flue gas streams, such as emitted from SSI units, the use of FFs is problematic due to plugging/fouling. In order to use carbon injection with a FF with high moisture streams, a waste heat boiler, RTO, or afterburner is necessary to maintain a high enough temperature to keep the stream above the dew point prior to sending the stream to the FF.

Therefore, we next evaluated the combination of using an afterburner, carbon injection, and FF for additional control of Hg at MH units. Additional equipment may also be necessary to reduce the temperature of the flue gas to prevent damage to the fabric filter bags. Sufficient information was not collected to estimate this cost. Table 10 of this preamble summarizes the cost for existing SSI units to apply different controls that were analyzed.

Table 10—Costs Expected for Existing SSI Units To Apply MACT Controls Analyzed

[2008$]

Control analyzed

Total capital costs

(million $)

Total annualized costs

(million ($/yr)

1—MACT Floor

2—MACT Floor + Afterburner for MH units

155

3—MACT Floor + Afterburner and Activated carbon injection and FF for MH units

490

138

Calculated using a seven percent discount factor.

Table 11 of this preamble summarizes the emission reductions of each pollutant for various controls analyzed.

Table 11—Summary of Emission Reductions for Existing Units To Apply the MACT Controls Analyzed

Pollutant

Emission Reductions for MACT Controls Analyzed (TPY)

MACT floor

MACT floor + afterburner for MH units

MACT floor + afterburner + ACI and FF for MH units

0.5-0.6

0.87-1.1

6,900-9,300

HCl

19-30

0.0022-0.0025

0.67-0.89

6.8-16

1.2-1.5

2.3-2.9

PCDD/PCDF TEQ

0.0000003-0.0000004

PCDD/PCDF TMB

0.000005-0.000007

58-70

300-400

430-700

The results provided in Tables 10 and 11 of this preamble were calculated using data gathered for each source (

e.g.,

emissions, vent gas flow rates, controls currently used), as well as default values for emissions, sludge capacity, and vent gas flow rate for sources where data were unavailable. We estimate that requiring the use of an afterburner for MH units not already having an afterburner could require as much as 1,010 million cubic feet of natural gas a year to be burned, resulting in NO

and CO emissions of 51 and 43 TPY, respectively. We estimate that applying activated carbon injection with a FF and an afterburner or RTO to all MH units to control Hg and PCDD/PCDF would result in total annualized costs of $138 million dollars (using a discount rate of seven percent) and would achieve Hg reductions of 0.67-0.89 TPY. The incremental cost-effectiveness of adding afterburners/RTO, activated carbon injection, and FFs to all MH units is estimated to be $80,000 to $100,000 per pound of Hg removed. Costs would increase if equipment necessary to cool the flue gas is also necessary. Therefore, given these factors, we are not finalizing any beyond-the-floor requirements for SSI units.

We also analyzed going beyond-the-floor to require packed bed scrubbers for additional HCl and SO

reduction, a wet ESP for additional PM, Cd and Pb reduction, and SNCR for additional NO

reduction. We determined that it was not appropriate to go beyond-the-floor to achieve greater reduction of HCl, SO

, PM, Cd, Pb, and NO

considering the cost and secondary impacts incurred. Our beyond-the-floor analyses for the final standards are documented in the memorandum “Revised Analysis of Beyond the Maximum Achievable Control Technology (MACT) Floor Controls for Existing SSI Units” (EPA-HQ-OAR-2009-0559).

F. Cost and Economic Impacts

Comment:

Commenters contended that EPA had underestimated the cost of the proposed rule for the beyond-the-floor option of Hg control as well as for the MACT floor for other pollutants because it only has information for less than 12 percent of the SSI units. The commenters added that EPA used information from these limited sources and applied it to remaining sources for which they did not have. The commenters contended that this results inaccurate determinations of which units could meet the proposed emission limits and which could not. The commenters contended that EPA overestimated the number of sources that could meet the proposed standards resulting in a significant underestimation of controls.

Some commenters also contended that EPAs choices of controls to cost for compliance with the proposed standards were inappropriate for SSI units. Many commenters stated that the high moisture content of flue gas streams in some applications may mean that FFs would not be an appropriate control for PM, Cd, or Pb.

Response:

EPA is not prescribing a specific control technology or method. A source is required to meet the final emissions limits in these standards, and has the flexibility to use the control method or technology that is best suited for their individual facility. EPA's costs are estimated based on technologies we believe may be appropriate for the sources to meet the emissions limits.

At proposal, and for the final standards, we estimated costs and emissions reductions based on the best available information to us. We acknowledge that the inventory database did not have complete information for all 204 SSI units. Consequently, we developed defaults for flue gas flow rate, hours of operation, sludge capacity, and other inputs for the proposed rule. We have updated our analyses using data provided by the commenters as summarized in section IV. Summary of Significant Changes Following Proposal and the memorandum titled, “Post-Proposal SSI Database Revisions and Data Gap Filling Methodology” in the docket (EPA-HQ-OAR-2009-0559). However, for a number of inputs, we are still assigning default values where data were not available for each SSI. For the final rule, we have correlated some of the defaults to populations served by the facilities in order to better estimate costs and emission reductions more specifically to each facility. Sources will have the best idea of the costs of controls for their site specific conditions. For some sources, the costs and emission reductions estimated by EPA may be higher than what the source estimates, and for others they will be less. EPA's estimates are estimates based on the best information available to us. We also note that the MACT floor costs and emission reductions, and determination of the number of sources estimated to require control, estimated for the final rule are also based on the revised MACT floor limits.

For the final standards we have also revised the types of controls costed to meet the MACT floor limits. For SSI that we estimate will need further control of PM, Cd, or Pb to meet the MACT floor, we have costed out wet ESP as a more appropriate PM control for high moisture streams. We have also costed out SNCR for SSI that we estimate will need further control of NO

to meet the MACT floor limits. As at proposal, we have costed out packed scrubbers for SSI that we estimate will need further control of HCl or SO

. At the MACT floor level, we do not estimate that any SSI will need to add control for Hg, PCDD/PCDF, or CO. A detailed discussion of the costs and emissions reductions estimates for the final

standards is provided in the memorandum “Revised Cost and Emission Reduction of the MACT Floor Level of Control” in the SSI docket (EPA-HQ-OAR-2009-0559).

Comment:

Commenters contended that EPA had incorrectly calculated the costs of the landfilling alternative because it used dry tons of sewage sludge instead of wet tons. The commenters added that wet tons is the appropriate basis of the sludge because even after the dewatering process, the sludge contains 70 to 80 percent moisture. Many of the commenters provided estimates for landfilling sludge from their specific unit. The commenters added that because of the error, EPA has significantly underestimated the impacts from transporting sludge by truck. Other commenters added that EPA had not evaluated the negative social impact of hauling sludge to a landfill. Some commenters added that EPA did not consider the additional costs for specific state landfilling regulations.

Several commenters contended that EPA incorrectly estimated the on-site sludge storage requirements because calculations were not done on a wet basis. Commenters added that the cost of the storage units would be significant and would need to include odor control as well as a settling basin.

Other commenters expressed concern regarding the availability of landfills to POTW needing disposal sites. The commenters contended there was insufficient landfill capacity to handle the influx of sewage sludge.

Response:

We have revised our costs and impacts of the landfill alternative based on comments received on the proposal and corrections made to the analysis. Table 14 of this preamble summarizes the revised costs and impacts of this alternative if small entities choose to landfill rather than incinerate sewage sludge. A detailed discussion of the landfilling alternative analysis is provided in the memorandum “Revised Cost and Emission Reduction of the MACT Floor Level of Control” in the SSI docket (EPA-HQ-OAR-2009-0559).

Based on the revised impacts, it is unlikely that many sources will find landfilling an appropriate alternative. The selection of a management option for sewage sludge is often a local decision that is based on environmental protection concerns, community needs, geographic constraints, and economic conditions. Given a full evaluation of these factors, for some sources, landfilling or land treatment may be a better management option than incineration.

G. Startup, Shutdown, and Malfunction

Comment:

Numerous commenters disagreed with EPA's proposed language requiring facilities to meet the proposed SSI standards “at all times” because it would be difficult to comply with certain proposed emission limits during startup and shutdown. Many of these commenters were specifically concerned about not being able to meet the proposed CO concentration limit upon startup of a SSI because when a heat up burner system is fired into a cold vessel, the flame tip is quenched before the combustion is completed creating a small flow of CO. One commenter contended that EPA is proposing a new source CO standard without any evidence that it can be achieved during startup, shutdown, or malfunction. This commenter provided an example of CO data from one hazardous waste combustor that averaged 2.2 ppmv during normal operations but averaged 48.6 ppmv during startup, 40.5 ppmv during shutdown, and 815.5 during malfunctions. The commenters stated that absolute pollutant levels tend to increase during startup and shutdown due to incomplete combustion that is unavoidable at lower temperatures, and noted that the influence of unstable combustion may be more pronounced during shutdowns as the incinerator combusts the remaining sewage sludge for 30 minutes or more. The commenters recommended that EPA account for situations where higher emissions occur during the time it takes to bring control equipment from startup to steady-state operations.

Response:

At this time, we are not promulgating a separate emission standard for the source category that applies during periods of startup and shutdown. We do not have data that would allow us to set a separate standard during periods of startup and shutdown. We requested information in the NPRM. However, no data were provided. Based on the information available at this time, we believe that SSI units will be able to meet the emission limits during periods of startup. Units we have information on use natural gas, landfill gas, or distillate oil to start the unit and add waste once the unit has reached combustion temperatures. Emissions from burning natural gas, landfill gas or distillate fuel oil are expected to generally be lower than from burning solid wastes. Emissions during periods of shutdown are also generally lower than emissions during normal operations because the materials in the incinerator would be almost fully combusted before shutdown occurs. Furthermore, the approach for establishing MACT floors for SSI units ranked individual SSI units based on actual performance for each pollutant and subcategory, with an appropriate accounting of emissions variability. Because we accounted for emissions variability, we believe we have adequately addressed any minor variability that may potentially occur during startup or shutdown.

Periods of startup, normal operations, and shutdown are all predictable and routine aspects of a source's operations. However, by contrast, EPA has determined that malfunctions should not be viewed as a distinct operating mode and, therefore, any emissions that occur at such times were not needed to be factored into development of CAA section 129 standards, which, once promulgated, apply at all times. We note that continuous compliance is demonstrated using continuous parametric monitoring, except for CO from new sources. CO CEMS are required for new source using a 24-hour block average.

Comment:

Some commenters argued that EPA incorrectly claims that its authority to prescribe unique standards for SSM periods is constrained by

Sierra Club

EPA,

551 F.3d 1019 (DC Cir. 2008). These commenters stated that EPA has failed to account adequately for emissions that occur during SSM periods. One commenter contended that the Sierra Club decision interpreted CAA section 112, not CAA section 129 (which incorporates, by reference, CAA section 111), and pointed out that this interpretation is not merely a technical distinction. The commenter pointed out that since 1977, EPA has exempted emissions during SSM events from compliance with NSPS under CAA section 111 (referenced 40 CFR 60.8(c)). The commenter argued that Congress enacted the continuous basis language in section 302(k) knowing that EPA`s emissions standards under section 111 exempted SSM periods, and pointed out that there is nothing in the legislative history of the 1977 amendments to the CAA that suggests congress intended to overturn that practice.

Response:

As explained above, EPA believes the reasoning in the DC Circuit's decision in

Sierra Club

EPA

applies equally to section 129. Additionally, EPA explains above the reasons it is not establishing different emissions standards for periods of startup, shutdown, and malfunction.

H. Compliance Requirements

Comment:

Several commenters indicated that the proposed operating parameter ranges for minimum pressure

drop across a wet scrubber, minimum scrubber liquid flow rate, minimum scrubber liquid pH, and minimum combustion temperature (or minimum afterburner temperature) would not be achievable. They explained that these ranges are too narrow and that they will be inconsistent with the operating standards already required by 40 CFR part 60 subpart O, 40 CFR part 503, and state permits. Two commenters agreed with the proposed operating parameter ranges.

Response:

The EPA reviewed the information provided by the commenters and determined that proposed procedure for establishing the operating ranges (

i.e.,

calculated as the average of three test runs and as 90 percent of the minimum value recorded during the applicable performance tests) may be too restrictive on control device operations in terms of energy or other operating needs. We determined that the operating limits should be more appropriately based on values recorded during the performance test runs. The final rule requires that operating limits be established on a site-specific basis as the minimum (or maximum, as appropriate) operating parameter value measured during the performance test. This approach has been incorporated into the final rule for all operating parameters and will result in achievable operating ranges that will ensure that the control devices used for compliance will be operated to achieve continuous compliance with the emissions limits.

Comment:

Many commenters argued that the proposed operating range for sludge feed rate would not be achievable, that it results in the EPA changing the current state-permitted maximum sludge feed rate, and that it could force SSI units to conduct performance tests at maximum rated capacity. They explained that the proposed approach fails to take into account the normal feed condition and rate variation that occur on a daily and seasonal basis. A few commenters suggested that charging a SSI at 75 percent to 90 percent of its rated capacity results in a steadier state of control and more efficient combustion of the sludge.

Many commenters indicated that the propos

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