Standards for Owners and Operators of Hazardous Waste ... · and part 261; and the associated...

Federal Register / Vol. 55, No. 82 / Friday, April 27, 1990 1 Proposed Rules

ENVIRONMENTAL PROTECTIONAGENCY

40 CFR Parts 260, 261,264 and 270

[FRL-3358-6 EPA/OSW/FR/9O-007J

RIN 2050-AB90

Standards for Owners and Operatorsof Hazardous Waste Incinerators andBurning of Hazardous Wastes InBoilers and Industrial Furnaces

AGENCY: Environmental ProtectionAgency.ACTION: Proposed rule, supplementalproposed rule, technical corrections, andrequest for comments.

SUMMARY: Under this proposal, theEnvironmental Protection Agency (EPA)would amend the hazardous wasteincinerator regulations to improvecontrol of toxic metal emissions,hydrogen chloride emissions, andresidual organic emissions; amend thedefinitions of incinerators and industrialfurnaces; propose definitions for plasmaarc incinerators and infraredincinerators; propose to regulate carbonregeneration units as thermal treatmentdevices; and make a number of minorrevisions to permitting procedures.

At present, toxic metal emissions fromincinerators are controlled indirectly bya limitation on particulate matter. Undersome conditions, the particulatestandard may not sufficiently controltxic metals to ensure adequateprotection of human health. Undertoday's proposal, EPA would establishrisk-based emission limits for individualtoxic metals in addition to the existingparticulate standard.

Under existing rules, hydrogenchloride emissions are controlled by atechnology-based standard. Becausethat standard may under-regulateemissions in particular situations, risk-based emissions limits would beestablished in addition to the existingstandard.

In addition, organic emissions thatresult from inadequate combustion oftoxic organic hazardous wastes arecontrolled under present rules by adestruction and removal efficiency(DRE) standard. The DRE standardrequires destruction of toxic organicconstituents in the waste, but does notdirectly control products of incompletecombustion. To address the potentialhealth risk from products of incompletecombustion, today's proposed rulewould require that incineratorscontinuously operate at high combustionefficiency by establishing limits on fluegas carbon monoxide and hydrocarbonlevels.

Finally, EPA is noticing technicalcorrections as well as requestingcomment on three regulatoryalternatives to issues presented in theOctober 26, 1989 supplement to theproposed rule for-burning hazardouswaste in boilers and industrial furnaces(54 FR 43718). These items are set forthin part One,-section III.C of this notice.The issues of concern are: regulationduring interim status of the directtransfer of hazardous waste from atransport vehicle to a boiler or furnace;controls on emissions of free chlorine;and limiting stack gas temperature atthe inlet to a dry emissions controldevice to below 450 *F.DATES: EPA will accept publiccomments on this proposed rule and onthe other issues opened for publiccomment by this notice until June 26,1990.ADDRESSES: Comments on this proposedrule, including the boiler and furnacesupplemental issues, should be sent toRCRA Docket Section (OS-305), U.S.Environmental Protection Agency, 401 MStreet, SW., Washington, DC 20460ATTN: Docket No. F-90-BWIP-FFFFF.The public docket is located in Room2427 and is available for viewing from 9a.m. to 4.p.m., Monday through Friday,excluding legal holidays. Individualsinterested in viewing the docket shouldcall (202) 475-9327 for an appointment.FOR FURTHER INFORMATION CONTACT:RCRA HOTLINE, at (800) 424-9346 (tollfree) or at (202) 382-3000. Single copiesof the proposed rule are available bycalling the RCRA Hotline. For technicalinformation, contact Shiva Garg,Combustion Section, WasteManagement Division, Office of SolidWaste, OS-322, U.S. EnvironmentalProtection Agency, 401 M Street, SW.,Washington, DC 20460, Telephone: (202)382-7924.SUPPLEMENTARY INFORMATION:

Preamble OutlinePART ONE: BACKGROUNDI. Legal AuthorityII. Overview of the Proposed Rule

A. Toxic MetalsB. Hydrogen ChlorideC. Control of Products of Incomplete

CombustionD. DefinitionsE. Permitting ProceduresF. Halogen Acid Furnaces

III. Relationship of the Proposed Rule toOther Rules

A. Existing Hazardous Waste IncineratorStandards

B. Other Related ActionsC. Technical Corrections To The October

26, 1989, Boiler/Furnace SupplementalNotice and Request For Comment OnRegulatory-Issues1. Technical Corrections.

2. Request for Comment on RegulatoryIssues.

D. Proposed Definition of Sludge DryerIV. Need for Controls

A. Risks From Toxic Metals EmissionsB. Risks From Hydrogen Chloride

EmissionsC. Potential Risks From Products of

Incomplete Combustion (PICs)

PART TWO: REGULATORY OPTIONSCONSIDERED

I. Particulate Emission LimitsA. Consideration of Controlling Metals

with a Particulate StandardB. Consideration of a More Stringent

Particulate StandardII. Definitions of Incinerators and Industrial

FurnacesA. Definition of Incinerator and Industrial

Furnace1. Revised Definition of IndustrialFurnace.2. Plasma Arc and Infrared Devices areIncinerators.3. Fluidized Bed Devices are Incinerators.4. Revised Regulatory Status of CarbonRegeneration Units.

B. Regulation of All Thermal TreatmentUnits Under Subpart 0

PART THREE: DISCUSSION OF PROPOSEDCONTROLS

I. Overview of EPA's Risk AssessmentA. Overview of the Risk Assessment

ApproachB. Identification of Reasonable Worst-Case

Incinerators by Terrain Type1. Factors Influencing Ambient Levels ofPollutants.

2. Selection of Facilities and Sites forDispersion Modeling

C. Development of Dispersion CoefficientsD. Evaluation of Health Risk

1. Risk from Carcinogens2. Risk from Noncarcinogens.

E. Risk Assessment AssumptionsF. Risk Assessment Guideline

II. Proposed Controls for Emissions of ToxicMetals

A. OverviewB. Metals of Concern1. Chromium.2. Nickel.3. Selenium.

C. Metals Emissions StandardsD. Screening Limits

Ill. Proposed Controls for Emissions ofHydrogen Chloride

A. Summary of Existing StandardB. The Existing Standard May Not Be Fully

Protective in Certain SituationsC. Request for Comment on Controls for

Free ChlorineD. Basis for Proposed Standards

IV. Proposed Controls for Emissions ofProducts of Incomplete Combustion

A. Hazard Posed by Emissions of Productsof Incomplete Combustion (PICs)B. Existing Regulatory ControlsC. Basis for CO Standards '1. Summary of Proposed Controls2. Use of CO Limits to Ensure GoodCombustion Conditions.

D. Derivation of the Tier I CO Limit.E. Derivation of the Tier II Controls.

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Federal Register / Vol. 55, No. 82 / Friday, April 27, 1990 / Proposed Rules

1. Health-Based Approach.2. Technology-Based Approach.a. Concerns with the THC RiskAssessment Methodology.b. Basis for the HC Limit.

F. Implementation of Tier I and Tier II PICControls

1. Oxygen and Moisture Correction.2. Formats of the CO Limit.3. Monitoring CO and Oxygen.4. Monitoring HC.5. Compliance with Tier I CO Limit.6. Establishing Permit Limits for CO underTier II.

7. Compliance with HC Limit of 20 ppmv8. Waste Feed Cutoff Requirements.

G. Request for Comment on Limiting APCDInlet Temperatures

PART FOUR: PERMIT PROCEDURES ANDOTHER ISSUES

I. Impact on Existing PermitsII. Waste Analysis Plans and Trial Burn

ProceduresA. Waste Analysis PlansB. Trial Burn Procedures

I1. Emergency Release StacksIV. POHC SelectionV. POHC SurrogatesVI. Information RequirementsVII. Miscellaneous IssuesVIII. Halogen Acid Furnaces

PART FIVE: ADMINISTRATIVE,ECONOMIC AND ENVIRONMENTALIMPACTS

I. State AuthorityA. Applicability of Rules in Authorized

StatesB. Effect on State Authorizations

I. Regulatory Impact AnalysisA. Purpose and ScopeB. Affected PopulationC. Costing Analysis

1. Costing Methodology and Unit Costs ofControl

2. ResultsD. Economic Impact Analysis

1. Methodology2. Results

F. Risk Assessment1. Methodology2. Results

G. Regulatory Flexibility Analysis1. Methodology2. Results

H. Paperwork Reduction ActII. Pollution Prevention ImpactsIV. List of Subjects in 40 CFR Parts 260, 264,

and 270Appendix A: Measurement of Metals and

Hydrogen Chloride

Today's preamble is organized in fivemajor parts. Part One containsbackground information thatsummarizes major provisions of the rule.It also describes how today's rule fitsinto the Agency's strategy for regulatingall burning of hazardous waste. Finally,this part identifies the need forincreased regulatory controls beyondthe present hazardous waste incineratorregulations.

Part Two discusses why the proposedcontrols limit emissions based on risk

assessment rather than usingtechnology-based standards. Part Twoalso discusses the proposed definitionsfor incinerators, industrial furnaces, andplasma arc and infrared incinerators;the regulation of carbon regenerationunits as thermal treatment devices; andminor revisions to existing permittingrequirements.

Part Three discusses the proposedrevisions to the existing emissionsstandards. It explains EPA's use of riskassessment to develop the proposedrule; describes conservative screeninglimits for toxic metals, hydrogenchloride, and total hydrocarbons; andexplains how site-specific dispersionmodeling would be used to establishemission limits when the screeninglimits are exceeded.

Part Four discusses the permitprocedures that would be used toimplement the controls, and alsodiscusses issues regarding the alreadyproposed listing of halogen acidfurnaces as industrial furnaces under§ 260.10. This section also explains theimpact of these proposed rules onexisting permits and the addedinformation requirements. Sampling andanalytical procedures that may be usedto analyze wastes for metals and todetermine actual metal emissions duringtrial burns are also discussed. Inaddition, this part discusses a number ofproposed revisions to permittingprocedures that would clarifyambiguities and provide more flexibilityto applicants and permit writers.

Part Five discusses the applicability ofthe rules in authorized States and theireffect on State authorizations. This partalso discusses the economic impacts therule would have on the regulatedcommunity.PART ONE: BACKGROUND

I. Legal AuthorityThese regulations are proposed under

authority of sections 1006, 2002, 3001through 3007, 3010, and 7004 of the SolidWaste Disposal Act of 1970, as amendedby the Resource Conservation andRecovery Act of 1976, the QuietCommunities Act of 1978, the SolidWaste Disposal Act Amendments of1980, and the Hazardous and SolidWaste Amendments of 1984, 42 U.S.C,6905, 6912, 6921 through 6927, 6930, and6974.

II. Overview of the Proposed RuleEPA proposes today to amend the

hazardous waste incinerator regulationsat 40 CFR part 264, subpart 0, part 260and part 261; and the associated permitrules at 40 CFR part 270 to provideimproved control of toxic metals

emissions, hydrogen chloride emissions,and residual organic emissions. EPAalso proposes to definition for sludgedryers and a revised definition forindustrial furnaces. Minor amendmentsto a number of permit requirements arealso proposed.

A. Toxic Metals

Wastes bearing high levels of metalsare commonly burned in incinerators(spent solvents and their still bottomsare examples). Metals and metalcompounds in hazardous waste are notdestroyed by incineration but aretransformed into other metal species(usually oxides) and then either areremoved as ash or in scrubber water, orare emitted with stack gases. Metals areusually emitted as particulates, but canbe emitted as metal vapors if the metalis volatile.

EPA has conducted risk assessmentsto determine the levels of toxic metalsthat would create an unacceptable riskto human health if released to theatmosphere. EPA's analysis indicatesthat the present hazardous wasteincinerator particulate standard of 0.08grain per dry standard cubic foot (180milligrams per dry standard cubic meter)may not adequately control emissions oftoxic metals.I

In 1982 and 1983, EPA conducted fieldstudies on eight incinerators to quantifyemissions of pollutants. The Agencythen evaluated the risk posed by thoseemissions and concluded that metalsemissions probably did not present anunacceptable level of risk. However, themetals levels in the waste feed to theincinerators in these tests wererelatively low. Emissions fromincinerators burning waste with highlevels of metals have not beendetermined in actual field tests. Thus,the Agency is concerned that, underconditions of high concentrations oftoxic metals in waste and inadequateflue gas cleaning methods, the potentialfor unacceptable levels of risk couldexist at some incinerators.

After considering the options forlimiting such potential risk, the Agencyis proposing to establish risk-basedemission limits for the individual toxicmetals listed in Appendix VIII of 40 CFRpart 261. The limits would be back-calculated from ambient levels that EPAbelieves pose acceptable health risk. Toreduce the burden to the applicant andpermitting officials, EPA has developedconservative Screening Limits. If the

1 Mitre Corp. "'Mitre Working Paper HazardousWaste Stream Trace Metal Concentrations andEmissions." USEPA, Office of Solid Waste.November 1983.

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Screening, Limits are not exceeded,emissions do not pose unacceptablerisk. If the Screening Limits are-exceeded, however, site-specificdispersion analysis would be-required todemonstrate that emissions would not.result in an exceedance of acceptableambient levels.

B. Hydrogen Chloride

EPA's present standard for control ofacid gas at 40 CFR 264.343(b) requiresthat the rate of emission of hydrogenchloride (HC1) be no greater than thelarger of 1.8 kilograms per hour (4pounds per hour) or I percent of the HC1in the stack gas before entering anypollution control device. EPA believesthat this standard may not be protectiveof public health in some instances. 2

Thus, EPA is proposing to regulate HC1under the same risk-based approachproposed for metals. The risk-basedcontrols would be used on a case-by-case basis to ensure that the existing-technology-based standard is protective.

C. Control of Products of IncompleteCombustion

Existing regulations control, organicemissions by thedestruction andremoval effeciency (DRE) standard at 40CFR 264.343(a). This standard limitsstack emissions of principal organichazardous constituents (POHCsJ to 0.01percent (0.0001 percent for dioxin-containing waste) of the, quantity of thePOHC fed to the incinerator. Thestandard considers a POHC to. bedestroyed (or removed in ash- orscrubber water) if it is not present in thestack emissions. EPA's. concern Is thatalthough the POHC itself may not bepresent at significant levels;intermediate combustion products, orproducts of incomplete combustion(PICs), may be present at levels thatcould pose. significant health risk. Thecomplete combustion of allhydrocarbons to produce only water andcarbon dioxide is theoretical and couldoccur only under ideal conditions. ReaL-world combustion systms (e.g.,incinerators, fossil fuel steamgenerators, diesel engines), however,virtually always, produce PICs, some. ofwhich could be highly toxic.

EPA believes that requiringincinerators to operate 'at high.combustion efficiency is a prudentapproach to minimize the potentialhealth risk posed by PIC, emissions.Given that stack gas COis aconventional indicator of combustionefficiency and a conservative indicator

IU.S. EPA, "Technical Background Document:Control of Metals and'Hydrogon:Chlorida Emissionsfrom Hazardous Waste Incinerators." August 1989.

of combustion- upsets (i.e., poorcombustion conditions, today's rulewould limit CO emissions to a deminimis level that ensures high,combustion efficiency and low unburnedhydrocarbon emissions..In cases wherethe de minimis CO limit is exceeded, theowner or operator would be required todemonstrate that higher CO levelswould not. result in high hydrocarbonemissions. We are taking comment ontwo alternative' approaches to ensurethat hydrocarbon emissions areacceptable: (1) A demonstration that'

hydrocarbon emissions are not likely topose unacceptable health risk usingconservative, prescribed riskassessment procedures; or (2) atechnology-based demonstration thatthe hydrocarbon concentration in thestack gas does not exceed a goodoperating practice-based limit of 20ppmv. Although we prefer thetechnology-based approach for reasonsdiscussed below, we request comment.on the health-based alternative as well.

D, DefinitionsEPA is today proposing revised

definitions for industrial furnaces and'incinerators and new definitions for,infrared incinerators and plasma arcincinerators. These definitions wouldinclude infraredand plasma arcincinerators within the definition ofincinerator and include nonflamecombustion devices within the definitionof industrial furnaces. EPA alsoproposes to regulate both direct flameand nonflame carbon regeneration unitsas thermal treatment units and, becauseof ambiguity regarding the currentregulatory status of'flame units, toestablish the date of promulgation as the"in existence" date for interim- status'EPA is also taking comment onanalternate regulatory approach thatwould simply regulate all types ofhazardous waste thermal treatmentdevices (e.g,. incinerators,. boilers;industrial furnaces) under one: set of'standards; subpart 0 of parts 264 and.265.,E. Permitting Procedures

The EPAis. today proposing to make-anumber of revisions to currentpermitting-.procedures, The purpose of.these revisions is to clarify ambiguitiesin the present regulations and to give thepermit writer flexibility in implementingthe rules while providing adequateprotection of-public health, Examples ofthese changes include: all- hazardouswaste combustion units at a sitewouldbe considered when implementing-therisk-based controls~proposed today;compounds may-be:chosen as POHCs'even though, they may not be on.

appendix VIIL or in the waste. (at the.permit writer's discretion);. informationrelating to emergency reliefvalves andtheir use must be provided in the part Bapplication; automatic waste feedcutoffs must be noted in an operating logand reported on a. quarterly basis; andtemperature must be maintainedin thecombustion chamber until all wastes,(and residues) exit the chamber.

We note that EPA has alreadypublished at 54 FR 4286 (January 30,.1989) clarifications to 40 CFR 270.62(d)which better reflect the initial intent. ofthe regulations with regard. to requiringexisting incinerators either to completea trial burn, or submit data in lieu, of atrial bum, prior to permit issuance.

F. Halogen Acid-Furnaces

On May 6, 1987, EPA proposed to addHalogen Acid Furnaces (HAFs) to thelist of industrial furnaces under § 260.10.See 52 FR 17018. We are todayrequesting comment on revisions to theproposed definition of HAFs to betterdistinguish between HAFs andincinerators burning:halogenated waste.In addition, we are proposing to list asinherently waste-like under § 261.2(d)any secondary material fed to a HAFthat is identified or listed as ahazardous- waste under part 261,subparts C or D. Without that listing,HAFs burning wastes solely'as aningredient (i.e., wastes that have lowheating value and, so, are not burnedpartially for energy recovery) to produceacid gas would be unregulated under§ 261.2(e)(l)(i). Wastes with high-heatingvalue (i.e. greater than 5,000 Btu/Ib), ,however, are considered to be burned atleast partially for energy recovery and,thus, would be subject to the proposedboiler and industrial furnace rules.

III. Relationship of the Proposed.Rule toOther Rules

A. Existing Hazardous WasteIncinerator Standards

The permit standards for incinerators.now in effect at 40 CFR part 264; subpart0, establish three performancestandards. The Agency believes thatthese standards may not be adequatelyprotective in all cases and, thus, is todayproposing to strengthen the-standards..

Incinerators burning hazardous wastemust achieve a destruction and removalefficiency [DRE) of 99.99 percent foreach Principal Organic Hazardous:Constituent (POHC) designated for eachwaste feed. This approach was based.upon-data. indicating the hazardouswaste incinerators burning a wide rangeof organic hazardous wastes couldachieve-such a destruction efficiency

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and risk assessments indicating levels ofunburned POHC would not pose anunacceptable health risk.

Metals emissions are controlledindirectly by a particulate matteremissions limit of 180 milligrams per drystandard cubic meter (or 0.08 gr/dscf).

Finally, hydrogen chloride (HC1)emissions are controlled by a standardthat requires emissions to be reduced by99 percent if emissions exceed 4 lb/hr.This standard is based upon theexpected HC1 removal efficiency fromexisting wet scrubber technology.

B. Other Related ActionsThe Agency has promulgated some

regulations and proposed others for theburning of hazardous waste in boilersand industrial furnaces that wouldensure that combustion controls andemissions standards are identical forboilers, industrial furnaces, andincinerators.

On January 4,1985, EPA revised itsrules to state that listed hazardouswastes and sludges are subject totransportation and storage controls priorto their being burned as fuels in boilersand industrial furnaces and prior to theirprocessing or blending to produce awaste-derived-fuel (50 FR 665).'OnNovember 29,1985, EPA promulgatedadministrative controls for marketersand burners of hazardous waste fuels(50 FR 49164) that included a provisionregulating transportation and storage ofany hazardous waste used as a fuel orused to produce a fuel.

On May 6, 1987, EPA proposed rulesthat would establish technical (i.e.,emissions) controls for boilers andindustrial furnaces burning hazardouswaste (52 FR 16982). The proposedboiler and industrial furnace ruleswould extend the concept of riskassessment to establish nationalperformance standards to control stackemission of metals and hydrogenchloride (HCI) and would controlproducts of incomplete combustion bylimiting flue gas carbon monoxidelevels. The rules would also require aDRE of 99.99 percent to bedemonstrated.

On October 26,1989, EPA published inthe Federal Register (54 FR 43718) asupplemental notice to the May 1987proposed rule. That notice requestedcomment on alternative approaches toaddress the following issues: control ofPIC emissions by limiting flue gasconcentrations of CO and hydrocarbons;control of metals, HCI and particulateemissions; the small quantity burnerexemption; the definition of waste thatis indigenous when processed forreclamation; applicability of theproposed metals and organic emissions

controls to smelting furnaces involved inmaterials recovery; and the status underthe Bevill amendment of residues fromburning hazardous waste. The PIC,metals, and HCI emission controlsproposed today for incinerators areidentical to those which the Agencyproposed for boilers and industrialfurnaces in the October 1989supplemental notice. As discussedbelow, the Agency is also today makingseveral technical corrections to theOctober 1989 notice. In addition, theAgency is requesting comment onseveral regulatory issues pertaining toboilers and industrial furnaces burninghazardous waste.

We note that EPA is also proposingtoday to amend the definition ofindustrial furnace to include devicesthat otherwise meet EPA's criteria forclassification as an industrial furnacebut that are heated by means other thancontrolled flame combustion (e.g.,electric arc smelting furnaces). Seesection III of part Two. Moreover, weare also requesting comment today onwhether and how to regulate allhazardous waste thermal treatmentdevices (e.g., incinerators, boilers, andindustrial furnaces) under parts 264 and265, subpart 0. Under this regulatoryscheme, we may be able to eliminate theneed for the sometimes ambiguousdistinction between boilers, industrialfurnaces, and incinerators and theredundant regulatory language thatwould occur if we promulgate boiler andindustrial furnace regulations (part 266,subpart D) as proposed, that arevirtually identical to existing andproposed regulations for incinerators.

Finally, we note that we arerequesting comments on several issuesregarding the proposed listing (52 FR17018) of halogen acid furnaces asindustrial furnaces under § 260.10.

C. Technical Corrections To TheOctober 26, 1989, Boiler/FurnaceSupplemental Notice And Request ForComment On Regulatory Issues

For convenience and because today'sproposed amendments to the incineratorstandards are closely related to theAgency's proposed boiler and industrialfurnace rules, the Agency is usingtoday's notice to make several technicalcorrections to the October 26, 1989,supplemental notice (54 FR 43718). Weare also requesting comment on severaladditional regulatory issues and arereopening the comment period on thesupplemental notice to take comment onthese issues.

1. Technical Corrections. The Agencyis making the following corrections toFRL-3358-5EPA/OSW-FR-89-024,Supplement to Proposed Rule for

Burning of Hazardous Waste in Boilersand Industrial Furnaces (54 FR 43718(October 26, 1989)):

a. On page 43720 under the heading"3. Apply Existing Hazardous WasteIncinerator Standard", the cite should be40 CFR 264.343(c), not 40 CFR 340.342(c).

b. On page 43731, the second equationshould read:

x y+ <1

140 40

c. On page 43757, footnote 56referencing the source for the HC1 RACof 7 ug/m3 should read "Memo datedMay 4, 1989, from Mike Dourson, EPAOffice of Health and EnvironmentalAssessment, to the RfD Workgroup,entitled "RfD Meeting of February 16,1989".

d. On page 43762 in Appendix I, thelong-term (i.e., annual) exposure RACfor HCI should be 7 fig/m 3, the 3-minuteexposure RAC for HCI should be 150pg/m 3, and the RAC for mercury shouldbe 0.3 pg/m.

e. On page 43763 in Appendix J, theunit risk for beryllium should be 2.4E-03m3/pg and the unit risk for a n-nitroso-n-methylurea should be 8.6 E-02 m3/jg.

2. Request for Comment onRegulatory Issues. The Agency isreopening the comment period on theOctober 26, 1989, supplemental notice totake comment on three issues: (a) theregulation during interim status of thedirect transfer of hazardous waste froma transport vehicle to a boiler orfurnace; (b) controls on emissions of freechlorine; and (c) limiting stack gastemperature at the inlet to a dryemissions control device (e.g., baghouse, ESP) to 450'F. (We note that weare reopening the comment period forthe October 26. 1989, supplementalnotice to receive comment on theseissues only.)

a. Transfer Operations. In the October26 supplemental notice (see page 43736),the Agency requested comment on twoapproaches to regulate direct transferoperations: (1) permit writers could usethe omnibus authority provided by thestatute to establish additional permitconditions as necessary to ensureadequate protection of human healthand the environment from suchoperations; and (2) a requirement thatall facilities that burn hazardous wasteuse blending and surge storage tanks toavoid flow interruptions and wastestratification, which, in turn, could affectthe ability of the combustion device tomeet the performance standards.

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During the comment period for theboiler/furnace supplemental notice,commenters suggested, that blending/.surge storage. tanks. were not necessaryto ensure compliance, with performancestandards. This issue will' be discussedfurther in. the promulgation of the final,boiler/furnace rules. Commenters alsostated,. however;, that controls ontransfer operations were needed during-interim status. They noted that it couldtake several years for the States or theAgency to issue-ar final permitto-a boileror furnace facility with a direct transferoperation. They argued that controlswere needed in the interim to ensureadequate protection of human healthand the enviromuent from spills, fires,explosions, and toxic fumes; We agreeand are today requesting comment onregulating direct transfer, operationsunder the appropriate interim status-standards for containers and tanksystems provided by Subparts I and J of40 CFR part 265, The other nontechnicalstandards for interim status facilities-couldialso, be applied, as applicable,including: subparts- A, B;. C,.I. E,.G, andH.

These standards would becomeeffective at the, same timethat the;interim. status, standards becomeeffective for the. boiler or. furnace,-six °

months after promulgation.The transport vehicle, once connected

to the boiler or furnace firing system,could be subject to the Subpart Icontainer standards. The once-a-weekihspection frequency provided-by§ 265.174, however, could be revised torequire daily inspection.

The piping system from the transportvehicle to the boiler or furnace could besubject to' the tank system standards of:Subpart J. We note that the compliancedates provided by Subpart'fJ could berevised to reflect the date of'promulgation ofa final rule.

In the final rule, we could revise the-subpart Iand I standards as indicatedabove and include them under-theboiler/furnace rules in subpart D of part,266.

The Agency requests comments on theneed to regulate. transfer operationsduring interim status and whether the-suggested revised standards would be,appropriate. The date of the final rulewould be the "in existence" date forpurposes. of interim status qualification;

b. Controls, for Emissions of FreeChlorine (C 2).. As discussed in sectionIII.B. of today's' proposal, we areconcerned that C12 could be emittedfrom burning chlorinated wastesif. therewas insufficient hydi'ogen available, (i~e.,.from other hydrocarbon compounds orwater vapor), to react with all the:chlorine in the waste. To, address, this

problem, we are requesting comment oawhether to require owners. andoperators of boilers and industrialfurnaces burning hazardous waste todemonstrate that the maximum exposed-individual (MEI-) is, not exposed to C12,concentrations, exceeding an annualaverage reference air concentration(RAC) of 0.. pg/m5 .2 The C2 RAC isbased on 100% of the. interim inhalationRfD because other sources of C6z; are,expected to have little-or no-effect onbackground levels due, to the short life. ofCl2 in the atmosphere. This approach isconsistent with the approach EPAproposed for HCI. As with the.HCIstandards, compliance could bedemonstrated, by: (1) emissions testingand dispersion modeling; (2) emissions,testing and conformance with C12emissions Screening Limits; or(3] wasteanalysis and conformance with. chlorinefeed rate Screening Limits.

The C12 Screening Limits could be ,developed, using- the same, methodologyused for the metals Limits (e.g., samedispersion or dilution factors; feed ratelimits assume all, chlorine-in the feed isemitted as, C6). (The dispersion factorsused to establish the HCI.ScreeningLimits would not.be appropriatebecause they are based on: short-term(i.e., 3-minute) exposures, A short-termRAC is not yet.available for CL,) Giventhat the: RAC for Cl2 is 1.33. times' theRAC for mercury, the Sireening, Limitsfor Clh would be-1.33,times, the. Limits-established, for mercury im Appendix: Eof the boiler/furnacesupplementaLnotice.

Emissions testing: for C6s. shoulctbeconducted in accordance. with "DraftMethod forDetermination: of HCIEmissions from Municipal and,Hazardous Waste- Incinerators", UIS.EPA, Quality Assurance Division, July,1989. In;using this method for C12 -determination, caustic impingers mustbe used after the water impingers in thesampling train. The caustic-solution willthen be analyzed for chloride and'reported as chlorine.

c..Limiting APCD Inlet Temperatures.We-are requesting comment on whetherto limit the temperature of stack gasentering- a dry emissions control' device(e.g., baghouse, electrostaticprecipitator (ESP)) to minimizeformation of chlorinated-dibenzodioxinand dibenzofurans (CDD/CDF). Afterconducting. extensive emissions testingof municipal' waste-combustors- (MWCs),the Agency has concluded that CDD/-CDF'can form- on MWC' fyash.in- the'

8 Mbmo from Priscilla Halloran, EPA, to DwightHlustick; EPA, entitled "HealthBased Air,Concentrations'for.Chlorihe and Nnitroso.n.methyluera',,.dated'franuar 4, 1990.

presence of excess oxygen- attemperatures. in. the range of 480 to750'F.4 Cooling the.flue gases andoperating the air pollution control. device(APCDJ. at temperatures below 450'Fhelps-minimize the formation of CDD/CDF' in the flue gas. Thus, the Agencyhas recently proposed to limit-MWCstack gas temperatures at the inlbtu to theAPCD'bo.450*F: See 54FR 52251(December 20, 198 9.

Given that some. hazardous wasteincinerators and boilers. and industrial.furnaces burning hazardous waste areequipped with dry particulate controldevices, we. request commenton the.need to, control gas temperatures to450"F to minimize CDD/CDF'formation.Although available-data indicate thatCDD/CDF'emissions fiom hazardouswaste combustion devices are muchlower than can be emitted from MWCs,5

it may be prudent to limit gas-temperatures in hazardous, wastecombustion devices as well.

E. Proposed Definition of Sludge D2'yer

We note. that the Agency-plans to,discuss- the regulatory status of sludgedryers and'propose. a new definition- forsuch devices in a separate, FederalRegister notice. This definition woulddistinguish between sludge dryers- andincinerators.. In that notice, the Agencyalso' wll propose to revise the definitiomof incinerator to exclude sludge dryers.that may otherwise meet the dbfinitionof incinerator. We summarize below thediscussion the Agency plans to presentin that notice

The notice will clarify the currentregulatory status of sludge dryers: (1)"sludge dryers that meet the §. 260.10definition of a tank 6 and a wastewater

4 See US EPA, "Minicipal Waste CombustionStudy: Combustion Control of Organic Eimission",

EPA/530-SW87--021C, NTIS Order No. P1387-206090, US EPA4 "Municipal Waste Combustion.Study: Flue Gas Cleaning Technology"; EPA/530-SW-87-021D, NTIS Order No. P1387-206108, and 54ER 52251.(December 20,1989).

5 See.discussibns in US-EPA, "BackgroundInformation Document for the Development of.Regulations for PICEmissions from HazardousWaste Incinerators", October 1989! {Draf-FinalReport), and Engineering Sciences; "BackgroundInformation Documentfor the Dbvelopment.ofRegulations to Control the-Burning otHhzardousWaste in-Boilers andIndustrial Furnaces; VolumeIII: Risk Assessment". February 1987. (Available.from the NationalTechinical Infbrmation Service,Springfield. VA, Order No. PB57173845.)

6 We-believe that virtually all-sludge dryers meetthe tank defihition-and therefore would be-exemptwhen used as part ofa.wastewater treatmentsystem.

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treatment unit are exempt fromregulation; and (2) sludge dryers that arenot exempt are subject to regulationunder part 265, subpart P or part 264,subpart X, as thermal treatment units,including those sludge dryers that meetthe current definition of an incinerator.Given that the Agency never intended toregulate as incinerators sludge dryersthat met the definition of incineratorwhen it was revised in 1985, nonexemptsludge dryers (those not meeting thedefinition of wastewater treatment unit)are subject to regulation under theinterim status standards of part 28subpart P, and the permit standards ofpart 264, subpart X, for other treatmentdevices. Accordingly, EPA plans topropose a revision to the incineratordefinition to explicitly exclude sludge.dryers.

To distinguish between sludge dryersand incinerators, EPA plans to proposethe following definition: "sludge dryer"means any enclosed thermal treatmentdevice used to dehydrate sludge andthat has a maximum thermal input (fromwastes and auxiliary fuel) of 1,500 BtuJlb of waste treated. EPA believes thatthis definition would clearly distinguishdryers from incinerators becauseincinerators require much higherthermal input-from 3,300 to more than19,000 Btu/lb of waste treated-toachieve the temperatures required todestroy organic compounds to levelsrequired by the subpart 0 destructionand removal efficiency standard. EPAbelieves that, for sludge dryers, the

7 In selecting a risk thresh of 10-5 for these rules,EPA considered risk thresholds in the range of 1c-

to 10- 6. As discussed in section .D. of Part Three ofthe text, the Agency requests comment onalternative risk thresholds.

6 An ME! location is sometimes defined in termsof current land use, i.e.. as that location wherepeople are currently exposed to the highest ambientpollutant concentrations. By this definition, MEI

thermal input is invariably less than1,500 Btu/lb.

IV. Need for Controls

A. Risks From Toxic Metals EmissionsThe Agency has determined that risks

from the burning of metal-bearinghazardous wastes in incinerators can beunacceptable under reasonable, worst-case circumstances, as defined byconcentrations of metals in theincinerated waste, incinerator capacityor feed rate, partitioning of metals tobottom ash, collection efficiency of"emission control equipment, and localterrain and meteorological conditions.For purposes of this rule, unreasonablerisks are considered to be either. (1)exceedance of incremental lifetimecancer risk of greater than 1X 10- 6 to thepotential maximum exposed individual(MEI) 7; or (2) exceedance at the MEl ofReference Air Concentrations (RACs)for noncarcinogens established as 25percent of the Reference Dose (RDs)(except that for lead, the RAC isestablished at 10 percent of the NationalAmbient Air Quality Standard and forHCI, the RAC is based directly oninhalation exposure studies). (Seediscussion in part three below.)

For the purposes of this regulation, theAgency conservatively defines themaximum exposed individual in termsof potential exposure: the MEI isassumed to be located where ambientpollutant concentrations created by afacility are highest, even if this locationis not currently populated. Thus, theconcentrations may be lower than maximumobserved concentrations. Since EPA's intention i tobe fully protective of health in the future as well asthe present. and since this analysis must generalizeon the basis of a sample of situations, we havedefined the MEl in terms of maximum potentialexposure. We also note that the ground-levelconcentrations of interest are the off-siteconcentrations except where people reside on site

potential MEl exposure predicitions aremore conservative than the actual MEIconcentrations.9

EPA has evaluated potential healthrisks from metals emissions underreasonable, worst-case scenarios.Conservative dispersion coefficients andambient levels of metals that poseacceptable health risk (see section I ofpart II) were used to estimate healthrisk from a liquid injection incineratorand a rotary kiln incinerator. See table1. Clearly, metals emissions can posesignificant health risk. For the liquidinjection incinerator analysis, we madethe following assumptions: (1) the wastefeed contained metals at the 50thpercentile level 9 according to our database, (2) all metals in the feed areemitted (i.e., emissions are notcontrolled, and no metals are removedwith the bottom ash); and (3) 10 percentof the chromium emitted is hexavalentchromium. For the rotary kilnincinerator, we made the followingassumptions: (1) the waste feedcontained metals at the highest levels inthe data base; (2) 0 to 5 percent of eachmetal is removed with the bottom ash;(3) the incinerator is equipped with aventuri scrubber (VS-20] to controlparticulate emissions that has a metalcollection efficiency as shown in tableG-3 of the boiler/furnace supplementalnotice (54 FR 43761 (October 26,1989));and (4) 10 percent of the chorimumemitted is hexavalent chromium.

such as military bases. colleges, and universities.Whether on site or off site ground-levelconcentrations will be considered in demonstratingconformance with the proposed controls will be leftto the discretion of the permit writer based onwhether people acutaly live on site.

' The data base is inadequate to derive percentilevalues. The values shown represent 50 percent ofthe highest levels of metals in the data base.

TABLE 1.-METALS EMIssioNs CAN POSE SIGNIFICANT RISK

Uquid Injection incinerator Rotary kiln incineratorMetal Concentrtion MEf cancer Ambient conc/ Concentration ME[ canc Ambient corc/

(ppm) risk RAG (Ppm) risk RAC

.CarcinogensArsenic . ... .... .... ........................ .. . ..... 25.0 tE-03 ...................... 500.0 4E-04 .........................

.et m ......................................................... 7.5 4E-06 .................... 16.0 2E-08Cadiu.... ...... . ................ 500.0 IE-02 ...... . I,000.0 SE-04Chromium (Vi) ... 1,725.0 3E-03 ................... 3,450.0 2E--05

NoncarcinogensAntimony ........ ............... ............ . ......... ................ 500.0 .......................... 2E+00 1,000.0 ..... .......... .... E-01Bariurr_.......... ... ......................... ....... 4,000.0 .............. TE-01 8,000.0 .......................... IE-03Lead-- .. 7,000.0' IE+02 14,000.0 2E-+01Mercury .. . . ....... 2.0 IE-03 4.0 . 9E-04

500.0 . 2E-01 1,000.0 4E-02Thalllum._........ . ...... - --........ 500.0 ... . .............. 2E+00 1,000.0... ........... 6E-0t

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B. Risks from Hydrogen ChlorideEmissions

EPA is today proposing to supplementthe existing technology-based HCIstandard with a standard based entirelyupon evaluation of health risk. Theexisting HCl standard requires that anincinerator control HCI emissions by 99percent or emit only 4 lb/hr (1.8 kg/hr).

The Agency has determined throughrisk assessments of reasonable, worst-case facilities that the short-termreference air concentration (RAC) forHCl can be exceeded under the existingrule. Thus, EPA is proposing to regulateHC1 under the same risk-basedstandard-setting approach proposed formetals. These standards will be in theform of site-specific risk analysisstandards, with conservative screeninglimits provided to ease the burden onthe applicant. For more information onthe proposed HCl standards, see PartThree, Section I: Proposed Controls forEmissions of Hydrogen Chloride.

C. Potential Risks from Products ofIncomplete Combustion (PICs)

The destruction and removalefficiency (DRE) approach to controlorganic emissions used in the presentregulations has some inherentlimitations. It does not control the actualmass of POHCs emitted since, for anygiven DRE, the mass emissions varydirectly in proportion to variations inmass feed rate. More importantly, theapproach fails to account directly foremissions of PIs, which can be as toxicas, or more toxic than, the POHCs.

As discussed in part Three of thispreamble, available data on PICemissions are limited. The studies donethus far indicate that emissions of toxicorganic compounds from incineratorscould result in an increased lifetimecancer risk of 10 - 6 (i.e., 1 in 1,000,000) topersons exposed to the maximumannual average ground-levelconcentration. The data base on PICemissions is limited, however, and thusthose risk assessments under-estimatethe risk. Those assessments consideronly the organic compounds that havebeen actually identified and quantified.Only 0 to 60 percent of total unburnedhydrocarbon emissions have beenchemically identified at any particularfacility. Thus, the bulk of thehydrocarbon emissions have not beenconsidered in those risk assessments.Although many of the unidentified,unquantified organic compounds may benontoxic, some fraction of the organicemissions is undoubtedly toxic.Considering that the available data arelimited, EPA believes it is prudent torequire incinerators to operate at a high

combustion efficiency to minimize thepotential health risks from PICemissions.

PART TWO: REGULATORY OPTIONSCONSIDERED

This part discusses the optionsconsidered by the Agency whendeveloping the standards proposedtoday.

I. Particulate Emission Limits

A. Consideration of Controlling Metalswith a Particulate Standard

The existing regulations control metaland some organic emissions through theperformance standard for particulates.Metals can be contained in particulatesor condense out onto particulates andare then captured by air pollutioncontrol devices. The present particulatestandard of 180 milligrams per drystandard cubic meter may not provideadequate protection if a substantialpercentage of the particulate iscomposed of toxic metals.1 0 Further, inthe case of volatile metals such asarsenic, mercury, and chlorides of leadand cadmium, the particulate standardmay provide little control.

Existing hazardous waste compositiondata make it difficult to estimate theaverage, or reasonable, worst-caselevels of toxic metals in wastes that areincinerated. In addition, as the Agencycontinues to prohibit land disposal ofuntreated hazardous waste, hazardouswastes with very high metals levels maybe incinerated in the future. Also, testingfor metals levels in incineratoremissions has been insufficient todetermine the average, or reasonable,worst-case levels of metals emissions tobe expected from hazardous wasteincinerators. However, there is nothingin the present regulations that wouldprohibit an incinerator operator fromintroducing extremely highconcentrations of toxic metal-containingwastes into an incinerator, therebycreating a situation that would presenthigh risks from toxic metals emissions.

Analysis of a hypothetical reasonable,worst-case situation indicates thatpresent rules may not be adequate tomaintain low levels of risk from toxicmetals under all possible scenarios.

Even relatively low concentrations oftoxic metals in wastes can result inunacceptable levels of risk if the wastesare burned in incinerators without airpollution control devices. Based uponthe 1981 mail survey,1 1 almost half of all

10 Mitre. op. cit. page 8.I I DPRA. 1981. Regulatory Impact Analysis Mail

Survey. Manhattan. Kansas.

interim status incinerators had no airpollution control device because, asliquid waste incinerators, they did notemit enough particulate matter torequire an air pollution control device tomeet the particulate standard of 180 mg/dscm.

It does not appear sufficient at thistime, in the Agency's judgment, to relysolely on a particulate standard as asurrogate for adequate control of toxicmetals. Given that there is virtually noupper bound in the levels of metals inhazardous wastes that may beincinerated (absent regulatory control),we have no assurance that theparticulate control provided by state-of-the-art technology would be adequate inall cases. Thus, we believe that the risk-based standards proposed today arepreferable to a technology-basedparticulate standard alone to controlmetals.

B. Consideration of a More StringentParticulate Standard

EPA is not proposing to revise at thistime the existing standard of 0.08 gr/dscf for the control of particulate matter(see 40 CFR 264.343(c)). This standardwas based on the new sourceperformance standard (NSPS) developedunder the Clean Air Act in 1979 for solidwaste incinerators. On December 20,1989, however, EPA proposed aparticulate emissions NSPS formunicipal waste combustors (MWCs) of0.015 gr/dscf. See 54 FR 52251. This morestringent standard takes advantage oftechnology advances made in the fieldof air pollution control.

The Agency has considered loweringthe hazardous waste incineratorparticulate standard of 0.08 gr/dscf to beconsistent with the proposed MWCstandard. However, reasonable, worst-case dispersion analyses show that theexisting particulate standard of 0.08 gr/dscf limits ambient levels generally toless than 30 percent of the 24-houraverage PM1o (particulate matter sizedless than 10 microns National AmbientAir Quality Standard (NAAQS), 150 pg/m . Further, we note that the existingparticulate standard would, undertoday's rule, be supplemented with risk-based standards to control emissions oforganic compounds and metals that maybe adsorbed on particulate matter. Inaddition, where a problem with theNAAQS is identified in a particulararea, the Agency or authorized Stateshould be including all sources ofparticulates in the State ImplementationPlans (SIPs). Therefore, if an incineratorcreates or aggravates a problem with theNAAQS, regulation of that source (withrespect to particulate emissions would

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be addressed under the SIP process orpotentially by a RCRA permit writerusing the omnibus permitting authority.

In developing today's proposed rule, anumber of people representing a widerange of interests (e.g., industryrepresentatives, environmentalists) haveindicated, however, that the rule may besimpler to implement and moreprotective if the controls weretechnology-based. They advocate usingrisk assessment only as a check todetermine if the standards are protectiveon a site-specific basis. They cite thecurrent limitations of risk-basedstandards in this particular situation,including: (1) indirect exposure (e.g.,uptake through the food chain) has notbeen considered for carcinogens; (2)metals controls are proposed only forthose metals for which sufficient healtheffects data exist to establish acceptableambient levels; and (3) the metalscontrols are difficult to implement bylimiting feed rates of individual metalsgiven the physical matrices of wastesand the variability of metalsconcentrations. We agree with theseconcerns and are initiating a testingprogram to develop technology-basedcontrols for particulate matter toprovide a measure of control forparticulates, including metal particulatesand adsorbed organic compounds,commensurate with best demonstratedtechnology (BDT) for hazardous wasteincinerators. See RCRA section3004(aJ(1)--section 3004 standards areto be revised periodically to take intoaccount improvements of measurementand technology. If EPA establishes aBDT particulate standard, the risk-basedcontrols for metals emissions would stillapply and would then be used as acheck to determine if the BDT standardprovides adequate protection on a case-by-case basis. Given the limitations ofcurrent risk assessment methodologies,we do not believe that it could bedemonstrated that a BDT standardsubstantially over-regulates in manysituations.

We are not proposing at this time tolower the existing particulate standardbecause we have not conductedadequate field testing of hazardouswaste incinerators to establish a BDTparticulate standard. 12 Further, once the

12 We note that several States control hazardouswaste incinerator particulate emissions to levelswell below EPA's standard of 0.08 gr/dscf. Inaddition, several hazardous waste incinerators havebeen demonstrated to be capable of routinelycontrolling particulate emissions to levels in the0.01-0.02 gr/dscf range, or less. Further. asdiscussed above in the text, the proposedparticulate standard for MWCs is 0.015 gr/dsd.Thus, we anticipate that a HOT particulate standardfor hazardous waste incinerators would be within-that range of 0.01 to 0.02 grtdscf.

BDT standard is identified, we wouldthen need to consider the impact on theregulated community of applying thestandard to establish a reasonablecompliance schedule.

I. Definitions of Incinerators andIndustrial Furnaces

We discuss below the basis forproposing to revise the definitions of

* incinerator and industrial furnace, theregulatory status for sludge dryers, anda request for comment on regulating allhazardous waste thermal treatmentdevices under parts 264 and 265, subpart0.

A. Definition of Incinerator andIndustrial Furnace

Existing definitions in § 260.10 forincinerators and industrial furnacesconsider how thermal energy isprovided to the device. Both definitionsstipulate that the device must utilizecontrolled flame combustion, thusexcluding devices using other means tosupply the heat necessary to combust orotherwise themally treat waste. Thus,for example, electric arc smelters arenot industrial furnaces and devicesusing infrared heat to destroy waste arenot incinerators. Significant regulatoryconsequences result from thesedeterminations. Electric arc smeltersthat reclaim nonindigenous metalhydroxide sludges are not industrialfurnaces, and, thus, are exempt fromregulation under § 261.6(c)(1), whilesmelters using direct flame combustionto reclaim the same sludge would beregulated under the May 6, 1987,proposed rules for boilers and industrialfurnaces. Infrared devices used todestroy waste would be regulated underthe subpart X permit standards of part264 and the subpart P interim statusstandards of part 265, while controlledflame incinerators would be regulatedunder subpart 0 of parts 264 and 265(and any amendments resulting fromtoday's proposal). The subpart X permitstandards under part 264 are notprescriptive; permit writers useengineering judgment and risk analysisto determine appropriate permitconditions.

We believe that incinerators andindustrial furnaces pose much the samerisk irrespective of whether they usecontrolled flame combustion or someother means to provide heat energy.Therefore, we are proposing to replaceor temper the reference to controlledflame combustion in respectivedefinitions.

1. Revised definition of industrialfurnace. We are proposing to revise thedefinition of industrial furnace to referto thermal treatment rather than to

controlled flame combustion. Webelieve that there are very fewadditional industrial furnaces (thatprocess nonindigenous waste) thatwould be regulated under this expandeddefinition, and it makes no sense toregulate these few furnaces differentlythan other industrial furnacesprocessing the same materials. EPAspecifically requests comments on theneed for the revised industrial furnacedefinition and resulant impacts on theregulated community.

2. Plasma arc and infrared devicesare incinertors We are proposing torevise the definition of incinerator toinclude explicitly two nonflamecombustion devices: plasma arc andinfrared incinerators. Although thesedevices are sometimes considered to benonflame devices rather thanincinerators, we believe that they shouldbe regulated as Subpart 0 incineratorsfor two reasons. First, they invariablyemploy afterburners to combusthydrocarbons driven off by the plasmaarc or infrared process. Thus, it can beargued that these units, in fact, meet thecurrent definition of an incinerator.Second, we believe that the Subpart 0incinerator standards can beappropriately applied to these devices;,the technical requirements of subpart 0are appropriate to address the hazardsposed by these devices. We also notethat applying the Subpart 0 standardswill reduce the burden on both permitwriters and applicants. The Subpart Xstandards are nonprescriptive standardsunder which permit writers apply permitconditions as appropriate to protecthuman health and the environment.Thus, under subpart X. permit writerswould need to determine on a case-by-case basis whether particular provisionsof subpart 0 are appropriate andwhether additional permit conditionswould be needed. Using Subpart 0strandards removes the ambiguity forboth permit writers and applicants overwhat requirements are necessary.

Today's proposed amendments to theincinerator standards likewise appearsuitable for plasma arc and infraredincinerators. We request comment onwhether there are other "nonflame"combustion devices for which theSubpart 0 incinerator standards areapplicable (i.e., devices that use anafterburner to combust hydrocarbonsgenerated from hazardous waste by anonflame process),

We note that we are proposing only tochange (or clarify) the regulatory statusof these two classes of devices, not tosubject them to regulation for the firsttime. Thus, interim status is not beingreopened for these devices. They have

I RRQ



been regulated since 1980 under subpartP (interim status standards for thermaltreatment units), subpart X (permitstandards for other treatment units), orsubpart 0 (interim status and permitstandards for incinerators). We notethat the interim status standards of part265, subpart P, are virtually identical tothe interim status standards of part 265,subpart 0.

3. Fluidized bed devices areincinerators. EPA would also like toclarify that fluidized bed devices areincinerators and are regulated undersubpart 0. They are not subject to thethermal treatment standards of part 265,subpart P, or requirements establishedunder part 264, subpart X. Fluidized bedincinerators are enclosed devices thatare designed to provide contact betweena heated inert bed material fluidizedwith air and the solid waste. Gas ispassed upwards through a column offine particulates at a sufficient velocityto cause the solids/gas mixture tobehave like a liquid. The bed ispreheated by overfired or underfiredauxiliary fuel. It is generally acceptedthat fluidized beds meet the definition ofincinerator, although there may havebeen some confusion in the past.Although we are clarifying that they domeet the definition of incincerator, wespecifically request comment onwhether there is sufficient ambiguity towarrant adding fluidized bed devices tothe definition of incinerator.

4. Revised regulatory status of carbonregeneration units. We are alsoproposing to revise the regulatory statusof carbon regeneration units. Controlledflame carbon regeneration unitscurrently meet the definition ofincinerator and have been subject toregulation as such since 1980,13 whilecarbon regeneration nonflame unitshave been treated as exemptreclamation units. We are proposing toregulate both direct flame and nonflamecarbon regeneration units as thermaltreatment units under the interim statusstandards of part 265, subpart P, and thepermit standards of part 264, subpart X.Our reason for doing this is that we areconcerned that emissions from thesedevices may present a substantialhazard to human health or theenvironment. We are not proposing to

13There appears to be confusion as to the currentregulatory status of direct flame activated carbonregeneration units. Because EPA indicated in theMay 19, 1980. preamble that all activated carbonregeneration units were engaged in a form ofrecycling presently exempt from regulation (45 FR33094). EPA Is proposing in this notice to amend theregulations to control these devices, both direct andindirect fired. Consequently, the "in existence" datefor all activated carbon regeneration units would bethe date of promulgation of final regulations.

apply the part 264, subpart 0,incinerator standards to these unitsbecause we are concerned thatdemonstration of conformance with theDRE standards (and the proposed CO/THC standards) may not be achievableconsidering the relatively low levels oftoxic organic compounds absorbed ontothe activated carbon.

The prevailing view appears to be thatcarbon regeneration units currently areexempt recycling units. We haveconsidered whether or not these unitstruly are engaged in reclamation, orwhether the regeneration of the carbonis just the concluding aspect of thewaste treatment process thatcommenced with the use of activatedcarbon to absorb waste contaminants,which are now destroyed in the"regeneration" process. 14 Irrespective ofwhether these units are better classifiedas waste treatment or recycling units (orwhether the units are flame or nonflamedevices), we are concerned, as indicatedabove, that emissions from theregeneration process can pose a serioushazard to public health if not properlycontrolled. Consequently, nonflameunits in existence on the date ofpromulgation (like flame units) would besubject to part 265, subpart P, and newunits would be subject to part 264,subpart X.

We note that we intend for thisproposal to also apply to those carbonregeneration units that meet thedefinition of wastewater treatment unitsin § 260.10 while they are in activeservice. These units would not beexempt from regulation when they arebeing regenerated because they are nolonger treating wastewater. Rather, theactivated carbon columns themselvesare being treated thermally.

B. Regulation of All Thermal TreatmentUnits Under Subpart 0

The Agency has done somepreliminary thinking on an alternativeapproach to regulating combustiondevices-the regulation of all thermaltreatment devices under virtuallyidentical standards under subpart 0.This would avoid a number of problemswith the current regulatory approach,including: (1) Ambiguous definitions forboilers and industrial furnaces; (2)incomplete coverage of the incineratorand industrial furnace definitions (e.g.,

14 We note that activated carbon units used as airemissions control devices frequently regenerate thecarbon in place by steam stripping, condensing theorganic contaminants for reuse. The trappedorganics in such columns are not hazardous wastesbecause the gas originally being treated is not asolid waste (it is an uncontained gas), and thereforeany condensed organics do not derive fromtreatment of a listed hazardous waste.

although today's proposal would expandregulatory coverage of industrialfurances to include heating by meansother than controlled flame combustion,furances other than those that are"integral'components of amanufacturing process" (see § 260.10),such as off-site facilities engaged solelyin waste management, could be engagedin bona fide reclamation and should beclassified as an industrial furnace ratherthan an incinerator); (3) the burden onthe regulated community and EPA andState officials to process petitions toclassify individual devices as boilers orindustrial furnaces rather thanincinerators; and (4) the numerousprovisions in the proposed boiler andfurnace rules that would merely parrotthe current and proposed incineratorstandards.

Under this alternative approach, allthermal treatment devices would beregulated under the same risk-basedstandards to control metals and HCIemissions-the standards proposedtoday for incinerators. 15 Control oforganic emissions could also be thesame as those CO controls proposedtoday for incinerators coupled with theexisting DRE standards for incinerators.Devices handling wastes with low levelsof toxic organic constituents (e.g.,smelters, sludge dryers, certainincinerators), however, would not besubject to organic emissions controls.The applicability of standards could, inmany cases, be a function of wasteproperties and composition. It may notbe necessary to identify applicability bytype of device.

EPA is continuing to consider thisalternative. In particular, we areinvestigating whether the temporaryexclusion for the special wastes inRCRA section 3001(b)(3) and the specialstandards and exemptions proposed forboilers and industrial furnaces can beimplemented without definitions forthese devices. We specifically requestcomments on this alternative regulatoryapproach whereby all thermal treatmentunits could be regulated under one set ofstandards under subpart 0.

PART THREE: DISCUSSION OF PROPOSEDCONTROLS

I. Overview of EPA's Risk Assessment

In developing this regulation, theAgency has used risk assessment to: (1)determine that absent regulatory

1s We note that EPA Is requesting comment onapplying these controls (as well as the proposed COcontrols) to boilers and industrial furnaces as wellin lieu of those proposed on May 6, 1987. See theFederal Register notice published today entitled."Burning of Hazardous Waste in Boilers andIndustrial Furnaces: Supplement to Proposed Rule."

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controls, emissions of products ofincomplete combustion, and certainmetals can pose significant healtheffects; (2) determine that the currenthydrogen chloride emissions standardmay not be fully protective in allsituations; and (3) establish risk-based,conservative emission Screening Limitsfor metals, hydrogen chloride (HC1), andunder one alternative approach,unburned hydrocarbons. The riskassessment methodology is discussed indetail in the background documentsupporting this proposed rule-Technical Background Document.Controls for Metals and HydrogenChloride Emissions for HazardousWaste Incinerators. The methodology issummarized below for the convenienceof the reader. 16

A. Overview of the Risk AssessmentApproach

EPA's risk assessment approachinvolves: (1) Establishing ambient level!of pollutants (i.e., metals, hydrogenchloride (HCI), and hydrocarbons (HC)that pose acceptable health risk; and (2)developing conservative dispersioncoefficients 17 for reasonable worst-casfacilities as a function of key parameter(i.e., effective stack height,18 terraintype, and land use classification). Toestablish the conservative ScreeningLimits for metals, HCI, and HC, weback-calculated from the acceptableambient levels using the conservativedispersion coefficients.

Under today's proposal, applicantswould be required to demonstrate thatemissions of metals, HCL, and (whenstack gas carbon monoxide :concentrations exceed 100 ppmv, andunder the health-based alternativeapproach to assess HC emissions) HCemissions do not result in an

16 We note that this discussion has beenpresented virtually verbatim in the October 26, 1989supplemental notice to the May 1987 proposedboiler and industrial furnace proposed rules. See 54FR 43752 (Appendix F). We have, however, mademinor revisions to that discussion to: (1) explicitlyrequest comment on alternative risk levels withinthe range of 10.5 to 10- , (2) better explain theAgency's selection of a 10" aggregate risk thresholdfor this rule; (3] explain that the Agency does notintend for the methodology used to establish theproposed reference air concentrations (RACs) toimply a decision to supplant standards establishedunder the Clean Air Act; and (4) request commentson whether the conservative assumptions used inthe risk methodology properly balance thenonconservative assumptions, or whether themethodology creates RACs that are unnecessarilystringent.

17 For purposes of this document, the termdispersion coefficient refers to the ambientconcentration that would result from an emissionrate of I gram/pec. This parameter is alsocommonly called a dilution factor.

Is Effective stack height is the height aboveground level of-a plume, based on summing thephysical stack height plus plume rise.

exceedance of the' acceptable ambient*levels. If the conservative ScreeningLimits are not exceeded, applicantsneed not conduct site-specific dispersionmodeling to make this demonstration.

In developing the conservativecoefficients and acceptable ambientlevels for metals, HCL, and HC, EPA alsofound that, under reasonable worst-casesituations, emission levels could poseunacceptable risk absent regulatorycontrols.

B. Identification of Reasonable Worst-Case Incinerators by Terrain Type

1. Factors influencing ambient levelsof pollutants. Ambient levels ofpollutants resulting from stackemissions are a function of thedispersion of pollutants from the sourcein question. Many factors influence therelationships between releases(emissions) and ground-levelconcentrations, including: (1) The rate of

3 emission; (2) the release specifications'of the facility (i.e., stack height, exitvelocity, exhaust temperature and innerstack diameter, which together definethe facility's "effective stack height"); (3)local terrain; and (4) local meteorologyand (5) urban/rural classification.

2. Selection of Facilities and Sites forDispersion Alodeling. Hazardous wasteincinerators are known to vary widelyin capacity, configuration, and design,making it difficult to identify typicalparameters that affect dispersion ofemissions (i.e., release parameters). Forinstance, stack heights of incineratorslisted in the 1981 survey 19 vary fromless than 15 feet to over 200 feet.Furthermore, many new facilities thatare now in operation that are not listedon the survey, and EPA expects that alarge number of additional facilities ofvarious types of designs are likely to beconstructed over the next several years.

For currently operating facilities, theworst-case dispersion situation wouldbe a combination of releasespecifications, local terrain, urban/ruralland use classification, and localmeteorology that produces the highestambient concentrations of hazardouspollutants per unit of pollutant releasedby a facility. This can be expressed, forany specific facility, as a dispersioncoefficient, which, for purposes of thisproposal, is the maximum annualaverage (or, as explained later, for HCl,maximum 3-minute) ground-levelconcentration for an emission of 1 g/s (aunit release); the units of the dispersioncoefficient are, therefore, pg/mS/g/s.20

19 DPRA, op. cit.20 Dispersion coefficients can be defined for any

specific location surrounding a release. Themaximum dispersion coefficient will, under the

Since dispersion coefficients are, as ageneral rule, inversely correlated witheffective stack heights, worst-casefacilities are most likely to be those withthe shortest effective stack heights. Nosimilar a priori judgment, however,should be made with respect to terrainor meteorology; evaluation of theinfluence of these factors requiresindividual site-by-site dispersionmodeling. It was therefore not possibleto screen facility locations in advance toselect for probable worst-case situationssimply by considering stack height.

Instead, out of a total number of 154existing facilities for which data wereavailable from the mail survey,21 weroughly sorted the facilities into threeterrain types based on broad-scaletopographic maps: flat, rolling, andcomplex terrain. We then ranked thefacilities by effective stack heights.Next, we evaluated terrain rise out to 50km for each of the 24 facilities andranked the facilities by maximumterrain rise. Finally, we subdivided the24 facilities into three groups which areloosely defined as flat, rolling, andcomplex terrain. In addition, to enableus to determine conservative dispersioncoefficients as a function of effectiveheight, we developed 11 hypotheticalincinerators and modeled each of these"incinerators" at the 24 sites. Thehypothetical facilities were selected bydividing the range of facilities listed inthe 1981 survey into 10 categories basedon effective stack height. Then, withineach stack height category, we selecteda hypothetical effective stack height thatapproximated the 25th percentile of therange of heights that existed within thecategory. The 25th percentile waschosen in order to select a facility likelyto reflect the higher end of dispersioncoefficients (and ambient levels) in eachheight category. In addition, an eleventhhypothetical source was defined inorder to represent facilities whoseheights of release do not meet goodengineering practice (see the discussionon good engineering practice in PartThree, 1 C, Site-Specific Risk AnalysisStandards). Such devices willexperience "building wake effects"-turbulence created by adjacentstructures that immediately mixes the

assumptions used in this regulation, be thedispersion coefficient for the MEI. It may occur atany distance and in any direction from the facility.However, locations within the property boundary ofa facility would not be considered whenimplementing these proposed rules unlessindividuals reside on site.

21 We note that the survey should berepresentative because it addressed over 50 percentof the 250 hazardous waste incinerators now inoperation.

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plume resulting in high ground-levelconcentrations close to the stack.

Finally, we also included the site thatresulted in the worst-case complexterrain conditions during developmentof the proposed rule for boilers andindustrial furnaces. 2 2 Although there iscurrently no hazardous wasteincinerator at that site, we used the siteas another theoretical location for the 11hypothetical incinerators and mergedthe results into those from the actualincinerator sites. Under certainconditions, this site provided higherdispersion coefficients for some stacks.

In summary, 11 hypothetical -incinerators and the actual incineratorswere modeled at each of 24 sites evenlydistributed among flat, rolling, andcomplex terrain. In addition, the 11hypothetical incinerators were modeledat an additional complex terrain site.

C. Development of DispersionCoefficients

Estimating the air impacts of thefacilities required the use of fiveseparate air dispersion models. We usedthe EPA Guideline on Air QualityModels (Revised),2 3 and consulted withthe EPA Office of Air Quality Planningand Standards to select the mostappropriate model for each application.

For each of the 25 locations, fiveconsecutive years of concurrent surfaceand twice-per-day upper air data (tocharacterize mixing height) wereacquired. The data sets containedhourly records of surface observationsfor five years, or approximately 44,000consecutive hours of meteorologicaldata. The same five-year data set wasused to estimate the highest hourlydispersion coefficient during the five-year period, and to estimate annualaverage concentrations based on a five-year data set for all releasespecifications modeled at each location.

The actual incinerator releasespecifications at each location wereused to select the appropriate model forshort-term and long-term averagingperiods. Once selected, the releasespecifications for the actual incineratorand the 11 hypothetical incineratorswere modeled. Table 2 lists the modelsselected.

22 See "Background Information Document for theDevelopment of Regulations to Control the Burningof Hazardous Waste in Boilers and industrialFurnaces, Volume Ill: Risk Assessment".Engineering-Sciences, February 1987. (Availablefrom the National Technical Information Service,Springfield, VA. Order No. PB 87 173845.)

23 USEPA. Guideline on Air Quality Models

(Revised). U.S. Environmental Protection Agency.Office of Air Quality Planning and Standards,Research Triangle Park, N.C. EPA-450/2/78-027R.July 1988.

TABLE 2.-MODELS SELECTED FOR THERISK ANALYSIS

Terrain Urbanl Averaging Modelclassifica- Rural period selected

tion

Flat or Urban or Annual ISCLTRolling. Rural average.

Flat or Urban or Hourly .......... ISCSTRolling. Rural.

Complex ..... Urban .......... Annual LONGZaverage.

Complex ..... Urban ........... Hourly .......... SHORTZComplex . Rural ............ Hourly or COMPLEX

annual. I

The Industrial Source Complexmodels (ISCLT and ISCST) wereselected for flat and rolling terrainbecause they can address buildingdownwash or elevated releases and canaccount for terrain differences betweensources and receptors. The long-termmode (ISCLT) was used for annualaverages, while the short-term mode(ISCST) was used to estimate maximumhourly concentrations.

To meet the EPA guidance on modelselection, we used three differentmodels to characterize dispersion overcomplex terrain. For urban applications,OAQPS recommends SHORTZ forshort-term averaging periods andLONGZ for seasonal or annualaverages. For rural sites located incomplex terrain, OAQPS recommendsthe COMPLEX I model.

We used U.S. Geological Survey 7.5-minute topographic maps to documentterrain rise out to 5 km from each stack.For purposes of this proposed rule, afacility is considered to be in flat terrainif the maximum terrain rise within 5 kmof the stack is not greater than 10percent of the physical stack height. Thefacility Is in rolling terrain if terrain riseis greater than 10 percent but not greaterthan the physical stack height, and incomplex terrain if terrain rise is greaterthan the physical stack height.24

We also used the topographic maps asthe basis to classify land use as urban orrural. A simplified version of the Auertechnique 25 based on the preferred land

24 We note that EPA can consider terrain wellpast 5 km of a stack to define terrain type for somefacilities. We believe, however, that a radius of 5km is adequate because we are concerned with ME1exposures (as opposed to aggregate populationexposures) and because the effective stack heightsof concern are relatively low in comparison tofacilities such as major power plants. Thus, MEexposures for the conditions modeled will alwaysoccur within 5 km of the stack.

28 Auer, August, H., Jr. Correlation of Land Useand Cover with Meteorological Anomalies. Journalof Applied Meteorology, Vol. 17, pp. 636-643, May1978.

use approach (rather than populationdensity) was used for this classification.If greater than 50 percent of the landwas classified as urban, the modelswere executed in the urban mode forthat facility. If greater than 50 percentwas classified as rural, the rural modeswere used.26

To identify conservative dispersioncoefficients as a function of effectivestack height, we graphically plotted foreach terrain type (i.e., flat, rolling, andcomplex) and each land useclassification (i.e., urban and rural)dispersion coefficients for the modeledfacilities and locations as a function ofeffective stack height. The outerenvelope iepresenting the highestdispersion coefficients was drawn toenable us to identify conservativecoefficients for any effective stackheight within the range of those modeled(i.e., 4 m to 120 m).

We determined that there was nosignificant difference in dispersioncoefficients (under the severe conditionsmodeled) between flat and rollingterrain. Thus, those terrain types weremerged together and termednoncomplex terrain. In addition, adiscontinuity was observed between theSHORTZ/LONGZ and Complex 127models, which resulted in our notdistinguishing between land useclassifications in complex terrain.Finally, we note that there was nosignificant difference in 3-minuteexposures between urban and rural landuse in either noncomplex or complexterrain. Thus, we have not distinguishedbetween land use classifications inestablishing the HC1 Screening Limits.There is, however, a significantdifference in maximum annual averagedispersion coefficients between urbanand rural land use in noncomplexterrain, and so we have establishedseparate metals and THC ScreeningLimits for those situations.

We note that the dispersioncoefficients used to establish theScreening Limits are designed to beconservative, but may, in fact, not beconservative in extremely poordispersion conditions, or when thereceptor (location (i.e., residence)) is

20 OAQPS guidelines indicate that 50 percent isthe cutoff point between urban and rural; however,to be conservative and to account for differences inthe accuracy of different measurement methods,EPA is recommending that for permitting purposesland use be considered urban if greater than 75percent is urban: that it be-considered rural if landuse is greater than 75 percent rural; and that if theland use is between 75 percent urban and 75 percentrural the more conservative Screening Limit of thetwo be used.

27 Complex I was found to produce relatively lowestimates of short-term concentrations.

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close-in to the source. Under thesituations identified below, theScreening Limits may not be protectiveand the permit writer should requiresite-specific dispersion modelingconsistent with EPA's Guideline on AirQuality Models (Revised) todemonstrate that emissions do not poseunacceptable health risk:

e Facility is located in a narrowvalley less than 1 km wide; or

* Facility has a stack taller than 20 mand is located such that the terrain risesto the stack height within 1 km of thefacility; or

e Facility has a stack taller than 20 mand is located within 5 km of theshoreline of a large body of water (suchas an ocean or large lake); or

* The facility property line is within200 m of the stack and the physicalstack height is less than 10 m; or

* On-site receptors are of concern,and the stack height is less than 10 m.

In addition to the situations identifiedabove, there is a probability, albeitsmall, that the combination of criticalparameters, stack height, stack gasvelocity, effluent temperature,meteorological conditions, etc., willresult in higher ambient concentrationsthan resulted from the conservativemodeling done to support this rule. As aresult, the Agency is reserving the rightto require that the owner or operatorsubmit, as part of the permit proceeding,an air quality dispersion analysisconsistent with EPA's Guideline on AirQuality Models (Revised) in order toensure that acceptable ambient levels ofpollutants are not exceeded irrespectiveof whether the facility meets the specificScreening Limits that would beesta'blished by this regulation.

Finally, we specifically requestcomment on whether less conservativeassumptions, coupled with a safetyfactor then,applied to assure thatambient levels are not underestimated,should be used to develop the ScreeningLimits. This alternative approach mayhave merit because the repeated use ofconservative assumptions in an analysismay "multiply" the conservatismunreasonably. Comments are solicitedon: (1) the extent to which lessconservative assumptions would enableapplicants to meet the Limits; (2) how toreduce the conservatism of theScreening Limits while still ensuring thatthey are protective; and (3) how thereduced conservatism would affect thecriteria discussed above that must beconsidered to determine if the ScreeningLimits are protective for a particularsituation. Note that, in section I.D. ofPart Three of the preamble, the Agencyrequests comment on basing thestandards on alternative risk thresholds.

D. Evaluation of Health Risk

1. Risk from Carcinogens. EPA cancerrisk policy suggests that any level ofhuman exposure to a carcinogenicsubstance entails some finite' level ofrisk. Determining the risk associatedwith a particular dose requires knowingthe slope of the modeled dose-responsecurve. On this basis, EPA's CarcinogenAssessment Group (CAG) has estimatedcarcinogenic slope factors for humansexposed to known and suspected humancarcinogens. Slope factors are estimatedby a modeling process. The slope of thedose-response curve enables estimationof a unit risk. The unit risk is defined asthe incremental lifetime risk estimatedto result from exposure of an individualfor a 70-year lifetime to a carcinogen inair containing 1 microgram of thecompound per cubic meter of air. Boththe slope factors and unit risks arereviewed by the Agency's Cancer RiskAssessment Validation Endeavor(CRAVE) workgroup for verification.

The unit risk values that the Agency isproposing to use for today's incineratoramendments are identical to those theAgency proposed for boilers andindustrial furnaces burning hazardouswaste. The unit risk values arepresented in Appendix J of the October26, 1989 Supplement to Proposed Rulefor boilers/furnaces. See 54 FR 43763.(We note that the unit risk for berylliumpresented in Appendix J should be 2.4E-03 m3/ug.) The acceptable ambient levelfor a carcinogenic compound is termedthe risk-specific dose (RSD) and isderived by dividing the acceptablehealth risk by the unit risk value. Asdiscussed below, the risk thresholdproposed for this rule is 10- .8 Thus,the RSDS for the metals that would beregulated by today's rules can becalculated by dividing 1X1O- 5 by theunit risk Values for the metals presentedin appendix J of the boiler/furnacesupplemental notice.2 9 The RSDs for the

28 In selecting a 1O- risk threshold for theserules, EPA considered risk thresholds in the range of10 - 4

to 10 - . As discussed in Section LD. of Part

Three of the text, the Agency requests comment onalternative risk thresholds.

29 We note, however, that the risk thresholdproposed for these rules is based on the aggregate(i.e., summed) risk for all carcinogenic metals. Thus,the RSD calculated by dividing 1X10 - 5 by the unitrisk value for a carcinogenic metal would be theacceptable ambient level if that were the onlycarcinogenic metal emitted. If other carcinogenicmetals are emitted, the allowable ambient level fora metal depends on the ambient levels of all thecarcinogenic metals. The sum of all carcinogenicmetals of the ratios of the actual ambient level tothe RSD cannot exceed one to ensure that theaggregate risk does not exceed iX10- .

metals are presented in appendix H ofthe boiler/furnace supplemental notice(see page 43762).

In setting acceptable risk levels todevelop today's proposed rule, weconsidered the fact that not allcarcinogens are equally likely to causehuman cancers, as discussed inGuidelines for Carcinogenic RiskAssessment (51 FR 33992 (September 24,1986)). The Guidelines have establisheda weight-of-evidence scheme reflectingthe likelihood that a compound causestumors in humans. The weight-of-evidence scheme categorizescarcinogens according to the quantityand quality of both human and animaldata as known, probable, and possiblehuman carcinogens. The proposedapproach places a higher weight oncancer unit risk estimates that are basedon stronger evidence of carcinogenicity.The proposed approach will provide formaking fuller use of information byexplicitly examining risk for differentcategories of carcinogens. In reachingthe conclusion of the level of cancerrisks to be used to support this proposal,we have considered availableinformation on the constituents beingemitted, the evidence associating thesecompounds with cancer risk, thequantities of emissions of theseconstituents, and the exposedpopulations.

For purposes of today's rule, we areproposing the following risk levels asacceptable incremental lifetime cancerrisk levels to the hypothetical maximumexposed individual (MEI): (1) for GroupA and B carcinogens, on the order of10-s; 30 and (2) for Group C carcinogens,on the order of 10- . These risk levelsare within the range of levelshistorically used by EPA in itshazardous waste and emergencyresponse programs-10- 4 to 10-

Under the weight-of-evidenceapproach to assess carcinogenic risk forthis proposed rule, we believe it isappropriate to add the risk fromcarcinogens within the category of thosethat are known or probable humancarcinogens, the Group A and Bcarcinogens. Such a group is composedof certain metals which cause lungcancer (arsenic, beryllium, cadmium,and chromium).

Similarly, it is appropriate to add therisk from carcinogens within thecategory of those that are probable orpossible human carcinogens, Ccarcinogens.

so A dose is calculated to correspond to a risk ofcausing cancer to one individual in one millionexposed to that dose over a lifetime.

IPYRF721 R /



To implement this carcinogenic riskassessment approach, we are proposingto limit the aggregate risk to the MEI to10- . This would limit the risk fromindividual carcinogenic metals to levelson the order of 10-6 but below 10- . Inselecting a 10- 5 aggregate risk thresholdlevel for this rule, we considered riskthresholds in the range of 10- 1 to 10-

the range the Agency generally uses forvarious aspects of its hazardous wasteprograms.

We considered limiting the aggregaterisk to the MEI to 10- 6 but determinedthat this risk threshold would beunnecessarily conservative for thepurpose of this rule. In reaching thisdetermination, we considered that, at anaggregate risk level of 10- 6, the risk levelfor individual metals would be on theorder of 10 - 7, which we believe is overlyconservative for this rule.

Alternatively, we considered limitingthe aggregate risk to the MEI to 10-. Anaggregate risk threshold of 10- 'wouldresult in limiting the risk level forindividual carcinogens on the order of10 - . We did not select a 10-' aggregaterisk threshold for this proposed rulebecause the risk assessmentmethodology used to establish emissionlimits considers only direct exposure tothe metals via inhalation of dispersedemissions. Other routes of exposure arenot accounted for by this methodology,which means risks could be somewhathigher. The Agency requests commentson the magnitude and nature of theserisks.

As noted above, the Agency hasproposed that an aggregate risk level of10- is appropriate in today's regulationbecause it would limit the risk level forindividual carcinogens to the order of10- . The Agency points out, however,that in selecting the appropriate risklevel for a particular regulatory program,it considers such factors as theparticular statutory mandate involved,nature of the pollutants, controlalternatives, fate and transport of thepollutant in different media, andpotential human exposure. These samefactors can also influence choice of arisk level where the Agency is makingsite-specific determinations.

The Agency would like to use theweight-of-evidence approach indeveloping the health-based alternativeapproach to assess hydrocarbon (HC)emissions under the Tier II PICcontrols.31 However, there are a number

31 We note that the following discussion in thetext pertains only to the health-based alternative forlimiting THC when CO exceeds 100 ppmv. Althoughwe request comment on the health-based approach,we prefer the technology-based approach of limitingTHC to a good operating practice-based level of 20

of unidentified compounds in the mix ofhydrocarbon emissions. Theseunidentified compounds could be eithercarcinogens or noncarcinogens, or both.Of the compounds that may becarcinogens, the Agency does not knowwhether they would be classified as A,B1, B2, or C carcinogens. Since theAgency cannot classify these unknowncarcinogens, the Agency is unable to usea weight-of-evidence approach to selectan acceptable risk level for HC. In orderto be conservative, the Agency isassuming that HC can be treated as asingle compound for which a unit cancerrisk is calculated. To derive this unitcancer risk value, the historical database of HC emissions from hazardouswaste incinerators, boilers, andindustrial furnaces was used. For eachorganic compound identified in theemissions, the 95th percentileconcentration value was taken as areasonable worst-case value. (Thehighest concentration was often usedbecause there were too few data toidentify the 95th percentile value.) Fororganic compounds listed in appendixVIII of part 261 for which health effectsdata are adequate to establish an RSDor RAC, but which have not beendetected in emissions from hazardouswaste combustion, an arbitrary emissionconcentration of 0.1 ng/L was assumed.The data base was further adjusted toincrease the conservatism of thecalculated HC unit risk value byassuming that the carcinogenformaldehyde is emitted from hazardouswaste combustion devices at the 95thpercentile levels found to be emittedfrom municipal waste combustors. Theproportion of the emission concentrationof each compound to the total emissionconcentration for all compounds wasthen determined. This proportion,termed a proportional emissionconcentration, was then multiplied bythe unit cancer risk developed by CAGto obtain a risk level for that compound.A unit risk of zero was used fornoncarcinogens like methane. All thecancer risks were added together toderive a weighted average 95thpercentile unit risk value for HC. Thisprocedure for developing a HC unit riskvalue assumes that the proportion of thevarious hydrocarbons is the same for allincinerators. In addition, it weighs allcarcinogens the same regardless ofcurrent EPA classification.

As explained in section IV of part IIIof the preamble, we are proposing tolimit hydrocarbon emissions-whenstack gas carbon monoxide levels

ppmv. See discussion in section IV of part Three ofthe text.

exceed 100 ppmv, and under the health-based alternative-based on a 10- 5

aggregate risk level.3 2 Thus, we arelimiting each of the constituents to a risklevel on the order of 10- .

Finally, in assessing the risk fromfacilities that emit both HC andcarcinogenic metals, we are notproposing that the risk from HCemissions be added to the aggregateMEI risk from metals emissions. Addingthe risk would be inappropriate becausewe do not know how all the HC wouldbe classified according to weight ofevidence. (We note again that we preferthe technology-based approach to limitHC emissions for reasons discussed insection IV of part III of the preamble.)

We specifically request comment onthis proposed approach to assesscarcinogenic risk. We also welcomesuggestions or alternative ways toaccount for additivity.

The Agency also requests comment onwhether aggregate population risk orcancer incidence (i.e., cancer incidentsper year) should also be considered indeveloping the national emission limitsand in site-specific risk assessments.This approach could, in some situations,be more conservative than consideringonly MEI risk because, even if the"acceptable" MEI risk level were notexceeded, large population centers maybe exposed to emissions such that theincreased cancer incidence could besignificant. However, it would bedifficult to develop acceptable aggregatecancer incidence rates. Nevertheless, itis likely that many facilities that performa site-specific MEI exposure and riskanalysis would also generate anaggregate population exposure and riskanalysis that could be considered by theAgency. Based on public comment andfurther thought on how to implementthis dual approach, the final rule couldincorporate consideration of both theMEI and aggregate population risk.Alternatively, EPA could provideguidance to the permit writer on whenand how to consider cancer incidenceon a case-by-case basis under authorityof section 3005(c)(3) of HSWA, ascodified at § 270.32(b)(2).

2. Risk from Noncarcinogens. Fortoxic substances not known to displaycarcinogenic properties, there appears tobe an identifiable exposure thresholdbelow which adverse health effectsusually do not occur. Noncarcinogeniceffects are manifested when these

32 In selecting a risk threshold of 10-5 for these

rules, EPA considered risk thresholds in the range of10- to 10-

. As discussed in Section LD. of partthree of the text. the Agency requests comment onalternative risk thresholds.

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pollutants are present in concentrationsgreat enough to overcome thehomeostatic, compensating, andadaptive mechanisms of the organism.Thus, protection against the adversehealth effects of a toxicant is likely to beachieved by preventing total exposurelevels from exceeding the thresholddose. Since other sources in addition tothe controlled source may contribute toexposure, ambient concentrationsassociated with the controlled sourceshould ideally take other potentialsources into account. The Agency has'therefore conservatively definedreference air concentrations (RACs) fornoncarcinogenic compounds that aredefined in terms of a fixed fraction ofthe estimated threshold concentration.The RACs for lead and hydrogenchloride, however, were establisheddifferently, as discussed below. TheRACs are identical to those the Agencyhas proposed for boilers and industrialfurnaces burning hazardous waste. Seeappendix H of the Supplement toProposed Rule at 54 FR 43762 (October26, 1989).83 (The Agency notes that itdoes not intend for RACs to be used asa means of setting air quality standardsin other contexts. For instance, the RACmethodology does not imply a decisionto supplant standards established underthe Clean Air Act.)

RACs have been derived from oralreference doses (RiDs) for thosenoncarcinogenic compounds listed inAppendix VIII of 40 CFR part 261(except for lead and hydrogen chloride)for which the Agency considers that ithas adequate health effects data. Anoral RfD is an estimate (with anuncertainty of perhaps an order ofmagnitude) of a daily exposure (viaingestion) for the human population(including sensitive subgroups) that islikely to be without an appreciable riskof deleterious effects even if exposureoccurs daily for a lifetime. Since theseoral-based RACs are subject to change,EPA contemplates publishing FederalRegister notices if the RACs change in away that affects the regulatory standard(see also the discussion of this issue inthe Boiler/Furnace supplemental noticepublished on October 26,1989 at 54 FR43718.)

The Agency is proposing RACsderived from oral RDs because itbelieves that the development of theRiDs has been technically sound andadequately reviewed. Specifically:

1. EPA has developed verified RfDs and iscommitted to establishing RfDs for allconstituents of Agency interest. Theverification process is conducted by an EPAworkgroup, and the conclusions and reasonsfor these decisions are publicly available.

2. The verification process ensures that thecritical study is of appropriate length andquality to derive a health limit for long-term,lifetime protection.

3. RfDs are based on the best availableinformation meeting minimum scientificcriteria. Information may come fromexperimental animal studies or from humanstudies.

4. RfDs are designed to give long-termprotection for even the most sensitivemembers of the population, such as pregnantwomen, children, and older men and women.

5. RiDs are designated by the Agency asbeing of high, medium, or low confidencedepending on the quality of the informationon which they are based and the amount ofsupporting data. The criteria for theconfidence rating are discussed In the RIDdecision documents.

The Agency used the followingstrategy to derive the inhalationexposure limits proposed today:

.1. Where a verified oral RID has beenbased on an inhalation study, we willcalculate the inhalation exposure limitdirectly from the study.

2. Where a verified oral RID has beenbased on an oral study, we will use aconversion factor of I for route-to-routeextrapolation in deriving an inhalation limit.

3. Where appropriate EPA healthdocuments exist, such as the Health EffectsAssessments (HEAs] and the Health Effectsand Environmental Profiles (HEEPs),containing relevant inhalation toxicity data,their data will be used in deriving inhalationexposure limits. We will also consider otheragency health documents (such as NIOSH'scriteria documents).

4. If RiDs or other toxicity data fromagency health documents are not available,then we will consider other sources oftoxicity information. Calculations will bemade in accordance with the RIDmethodology.

The Agency recognizes the limitationsof roue-to-route conversions used toderive the RACs and is in the process ofexamining confounding factors affecting

the conversion, such as: (a) theappropriateness of extrapolating when aportal of entry Is the critical targetorgan; (b) first pass effects; and (c)effect of route on dosimetry.

The Agency, through its InhalationRD Workgroup, is developing referencedose values for inhalation exposure, andsome are expected to be available thisyear. The Agency will use the availableinhalation RfDs-after providingappropriate opportunity for publiccomment-when this rule ispromulgated. Certainly, if the workgroupdevelops inhalation reference dosesprior to promulgation of today's rule thatare substantially different from theRACs proposed today, and if the revisedinhalation reference dose could beexpected to have a significant adverseimpact on the regulated community, theAgency will take public comment on therevised RACs after notice in the FederalRegister.

EPA proposed this same approach forderiving RACs on May 6, 1987 (52 FR16993) for boilers and industrial furnacesburning hazardous waste. We received anumber of comments on the proposedapproach of deriving reference airconcentrations (RACs) from oral RDs.As stated in today's proposal and theMay 6, 1987, proposal, we would preferto use inhalation reference doses. Somecomments suggested other means ofderiving RACs. We will consider thosecomments and others that may besubmitted as a result to today's proposalin developing the final rule.

As previously stated, EPA has derivedthe RACs from oral reference doses(RfDs) for the compounds of concern. Anoral RfD is an estimate of a dailyexposure (via ingestion) for the humanpopulation that is likely to be without anappreciable risk of deleterious effects,even if exposure occurs daily throughouta lifetime.8 4 The RfD for a specificchemical is calculated by dividing theexperimentally determined no-observed-adverse-effect-level (NOAEL) or lowest-observable-adverse-effect-level(LOAEL) by the appropriate uncertaintyfactor(s). The RAC values inherentlytake into account sensitive populations.

The Agency is proposing to use thefollowing equation to convert oral RiDsto RACs:

RiD (mg/kg-bw/day) x body weight X correction factor < background level factorRAC (mg/m} =

111 air breathed/day

31 Note that the RAC for HCI presented inAppendix I of the Boiler/Furnace supplementalnotice is incorrect. The long-term (i.e., annual)exposure RAC should be 7 Ag/m. and the 3-minuteexposure RAC should-be 150 pg/m.

34 Current scientific understanding, however,does not consider this demarcation to be rigid. Forbrief periods end for small excursions above theRID, adverse effects are unlikely in most of thepopulation. On the other hand, several

circumstances can be cited In which particularlysensitive members of the population suffer adverseresponses at levels well below the RiD. See 51 FR1627 (January 14.100).

1WI72:1 11 :



where:" R11D is the oral reference dose" Body weight (bw) is assumed to be 70 kg

for an adult male* Volume of air breathed by an adult male

is assumed to be 20 mSper day" Correction factor for route-to-route

extrapolation (going from the oral routeto the inhalation route) is 1.0

" Background level factor is 0.25. It is afactor to fraction the RID to the intakeresulting from direct inhalation of thecompound emitted from the source (i.e.,an individual is assumed to be exposedto 75 percent of the RfD from thecombination of indirect exposure fromthe source in question and othersources).

a. Short-term exposures. In today'sproposed rule, the RACs are used todetermine if adverse health effects arelikely to result from exposure to stackemissions by comparing maximumannual average ground-levelconcentrations of a pollutant to thepollutant's RAC. If the RAC is notexceeded, EPA does not anticipateadverse health effects. The Agency,however,is also concerned about theimpacts of short-term (less than 24-hour)exposures. The ground-levelconcentration of an emitted pollutantcan be an order of magnitude greaterduring a 3-minute or 15-minute period ofexposure than the maximum annualaverage exposure. This is becausemeteorological factors vary over thecourse of a year resulting in a widedistribution of exposures. Thus,maximum annual averageconcentrations are always much lowerthan short-term exposureconcentrations. On the other hand, theshort-term exposure RAC is alsogenerally much higher than the lifetimeexposure RAC. Nonetheless, in somecases, short-term exposure may pose agreater health threat than annualexposure. Unfortunately; the use of RfDslimits the development of short-termacute exposure limits because noacceptable methodology exists for thederivation of less than lifetime exposurefrom the RfDs. a s However, despite theselimitations, the Agency is proposing ashort-term (i.e., 3-minute) RAC for HC1of 150 pg/ml, based on limited datadocumenting a no-observed-effect-levelin animals exposed to HC1 viainhalation.8 8 We do anticipate,

35 Memo from Clara Chow through RevaRubenstein, Characterization and AssessmentDivision. EPA. to Robert Holloway, WasteManagement Division, EPA. entitled "Use of RfDsVersus TLVs for Health Criteria." January 13, 1987.

86 Memo from Lisa Ratcliff, Characterization andAssessment Division to Dwight Hlustick, WasteManagement Division. October 2,1988, interpretingresults from Sellakumar, A.R.: Snyder, C.A.;Solomon. I.J.; Albert R. (1985) Corcinogenicity of

however, that short-term RACs for othercompounds will be developed by theAgency in the future.

b. RACfor HC1. The RAC for annualexposure to HC1 is 7 pg/m s

37 and isbased on the threshold of its priorityeffects. Background levels wereconsidered to be insignificant given thatthere are not many large sources of HC1and that this pollutant generally shouldnot be transported over long distancesin the lower atmosphere. The RAC for 3-minute exposure is 150 pg/m 3.8 Asnoted above, EPA also proposed theseRACs for HC1 in the boiler and furnaceproposed rule. See 54 FR 43718 (October28, 1989). The Agency requests commenton whether the conservativeassumptions used in its methodologyproperly balance the nonconservativeassumptions, or whether themethodology creates RACs that areunnecessarily stringent.

c. RAC for Lead. To consider thehealth effects from lead emissions, weadjusted the National Ambient AirQuality Standard (NAAQS) by a factorof one-tenth to account for backgroundambient levels and indirect exposure

* from the source in question. Thus,although the lead NAAQS is 1.5 pg/m s,

for purposes of this regulation, sources,could contribute only up to 0.15 pg/m .

Given, however, that the lead NAAQS isbased on a quarterly average, however,the equivalent annual exposure Is 0.09Ig/m

3 for a quarterly average of 0.15pg/m. Thus, the lead RAC is 0.09 pg/m3.EPA has also proposed this RAC inthe boiler and furnace proposed rule.See 52 FR 17006.

d. Relationship to NAAQS. The CleanAir Act (CAA) requires EPA to establishambient standards for pollutantsdetermined to be injurious to publichealth or welfare. Primary NationalAmbient Air Quality Standards(NAAQS) must reflect the level ofattainment necessary to protect publichealth allowing for an adequate marginof safety. Secondary NAAQS must bedesigned to protect public welfare inaddition to public health, and, thus, aremore stringent.

As discussed above, the Reference AirConcentration (RAC) proposed today forLead is based on the Lead NAAQS. Asthe Agency develops additional NAAQSfor toxic compounds that may be

Formaldehyde and Hydrogen Chloride in Rats.Toxicol. Appl. Pharm. 81:401-408.

01 Memo dated May 4.1989, from Mike Dourson.

EPA Office of Health and EnvironmentalAssessment. to the RID Workgroup, entitled RIDMeeting of February 16,1989.

88 Memo from Lisa Ratcliff, EPA. to DwightHiustick. EPA, entitled "Short-term Health-basedNumber for Hydrogen Chloride," September 15.1986.

emitted from hazardous wasteincinerators, we will consider whetherthe acceptable ambient levels (and,subsequently, the feed rate and emissionrate Screening Limits) ultimatelyestablished under this rule should berevised.

The reference air concentration values(and risk-specific dose values forcarcinogens) proposed here in no waypreclude the Agency from establishingNAAQS as appropriate for thesecompounds under authority of the CAA.

E. Risk Assessment Assumptions

We have used a number ofassumptions in the risk assessment,some conservative and othersnonconservative, to simplify theanalysis or to address issues wheredefinitive data do not exist.

Conservative assumptions include thefollowing:

e Individuals reside at the point ofmaximum annual average and (for HCI)maximum short-term ground-levelconcentrations. Furthermore, risk estimatesfor carcinogens assume that the maximumexposed individual resides at the point ofmaximum annual average concentration for a70-year lifetime.

o Indoor air contains the same levels ofpollutants contributed by the source asoutdoor air.

* For noncarcinogenic healthdeterminations, background exposurealready amounts to 75 percent of the RID.This includes other routes of exposure,including ingestion and dermal. Thus, theincinerator is only allowed to contribute 25percent of the RID via direct inhalation. Theonly exception is for lead, where anincinerator is only allowed to contribute 10percent of the NAAQS. This is becauseambient lead levels in urban areas alreadyrepresent a substantial portion (e.g., one-thirdor more) of the lead NAAQS. In addition, theAgency is particularly concerned abouthealth risks from lead in light of healtheffects data available since the lead NAAQSwas established. EPA is currently reviewingthe lead NAAQS to determine if it should belowered.8 9

39 At this point, we have not attempted toquantify indirect exposure through the food chain.ingestion of water contaminated by deposition, anddermal exposure, because as yet no acceptablemethodology for doing so has been developed andapproved by the Agency for use for evaluatingcombustion sources. We note, however, that byallowing the source to contribute only 25 percent otthe RiD (or 10 percent of the NAAQS in the case oflead) accounts for indirect exposure by assuming aperson is exposed to 75 percent of the RiD fromother sources and other exposure pathways. (EPAhas developed such a methodology for applicationto waste combustion sources. The Agency's ScienceAdvisory board has reviewed this methodology, andthe Agency is continuing to refine the methodology.When the Agency completes development ofprocedures to evaluate indirect exposure, a moredetailed analysis may be applied to incineratorsburning hazardous wastes.)

1787617876__i



e Risks are considered for pollutants thatare known, probable, and possible humancarcinogens.

* Individual health risk numbers havelarge uncertainty factors implicit in theirderivation to take into effect the mostsensitive portion of the population.

Nonconservative assumptions includethe following:

9 Although emission are complex mixtures,interactive effects of threshold orcarcinogenic compounds have not beenconsidered in this regulation because data onsuch relationships are inadequate.40

* Environmental effects (i.e., effects onplants and animals) have not beenconsidered because of a lack of adequateinformation. Adverse effects on plants andanimals may occur at levels lower than thosethat cause adverse human health effects.(The Agency is also developing proceduresand requesting Science Advisory Boardreview to consider environmental effectsresulting from emissions from all categoriesof waste combustion facilities.)

F. Risk Assessment Guideline

EPA proposes to implement the risk-based controls for metals, HCI, and(under the health-based alternative)THC emissions using procedures andinformation presented in today'spreamble. The procedures andinformation would be provided to permitwriters in a document that would beentitled Risk Assessment Guideline forPermitting Hazardous Waste ThermalTreatment Devices (RAG). The RAGwould be incorporated by reference inthe rules at § 270.8. Although thedocument has not yet been written, itwould include Information presented intoday's notice such as: (1) RACs andRSDs for pollutants of concern (i.e.,metals, HCI, and THCs); (2) ScreeningLimits for metals, HCI, and THCs; and(3) procedures for reviewing site-specificdispersion modeling plans and resultssubmitted by applicants. The RAGwould be published concurrently withfinal promulgation of the amendmentsproposed today.

In lieu of providing this information ina guidance document, we areconsidering codifying it as part of theregulation. Our concern is that guidancedocuments do not carry the weight of aregulation-permit writers would be freeto accept or reject the guidance (e.g.,Screening Limits, RACs, RSDs) andwould be obligated to justify use andappropriateness of the guidance on acase-by-case basis. This could place asubstantial burden on the permit writerand result in inconsistent and, perhaps,inappropriate permit conditions. We

4 Additive effects of carcinogenic compoundsare considered by summing the risks for allcarcinogens to estimate the aggregate risk to themost exposed Individudl (MEI).

specifically request comment onwhether the Screening Limits, RACs,and RSDs should be codified.

I. Proposed Controls for Emission ofToxic Metals

A. Overview

As in the proposed rule on the burningof hazardous waste in boilers andindustrial furnaces (see 52 FR 16982(May 6, 1987) and 54 FR 43718 (October26, 1989)), EPA is proposing to controlmetals emissions by requiring a site-specific risk analysis when metalsemissions (or feed rates) exceedconservative Screening Limits. EPAdeveloped the Screening Limits tominimize the need for conducting site-specific risk assessments, therebyreducing the burden to applicants andpermit officials. When the ScreeningLimits are exceeded, the applicantwould be required to conduct a site-specific risk assessment thatdemonstrates that the potentialexposure of the maximum exposedindividual to carcinogenic andnoncarcinogenic metals does not resultin an exceedance of reasonableacceptable marginal additional risks,namely:

* That exposure to all carcinogenic metalsbe limited such that the sum of the excessrisks attributable to ambient concentrationsof these metals does not exceed an additionallifetime individual risk (to the (potential)maximum exposed individual} of 10- 5 41; and

* That exposure to each noncarcinogenicmetals be limited such that exposure (to the(potential) maximum exposed individual)does not exceed the reference airconcentration (RAC) for the metal.

B. Metals of Concern

Although the limited data available onmetals composition of incinerated wasteindicates that some of the 12 AppendixVIII metals may not pose unacceptablehealth risk (i.e., either because no wasteconcentration data are available for aparticular metal or because theavailable data indicate that a metal isnot present at a particular facility atlevels that would pose unacceptablerisk), EPA nonetheless is proposingstandards to control emissions of all 12Appendix VIII metals, except forselenium and nickel as discussed below.We believe that controls are needed forthe other 10 metals-the carcinogensarsenic, beryllium, cadmium, andchromium VI and the noncarcinogensantimony, barium, lead, mercury, silver,and thallium-because our waste

41 In selecting a risk threshold of0- *for theserules, EPA considered risk thresholds in the range of10-'to 10- . As discussed in Section I.D. of Part 'Three of the text, the Agency requests comment onalternative risk thresholds.

composition data base is both limitedand outdated, especially considering theAgency's efforts (and statutorymandate) to require treatment of waste,often by incineration, prior to landdisposal. We have no assurance thatany particular waste to be burned in anincinerator would not contain levels ofany of the 10 metals that could result inunacceptable health risk. Rather thanestablishing controls for the four or fivekey metals (e.g., arsenic, cadmium,chromium VI, and lead) and requiringpermit officials to determine on a case-by-case basis whether other metals arepresent at levels that could poseunacceptable risk and controlling thoseemissions under the Section 3005(c)(3)omnibus provision of HSWA (codifiedat § 270.32(b)(2)), we believe it is morestraightforward and less burdensome onboth applicants and permit officials toestablish controls for all 10 metals. Wenote that although EPA proposed tocontrol boiler and furnace emissionsonly for the metals arsenic, cadmium,chromium, and lead, and to requirepermit writers to determine the need tocontrol other metals on a case-by-casebasis (see 52 FR 17005), the Agency hasrequested comment in a supplementalnotice to the boiler/furnace proposedrules on promulgating controls on all 10metals. See 54 FR 43718 (October 26,1989).

The basis for controlling emissions ofchromium only in the hexavalent formand for not establishing controls fornickel and selenium is discussed below.

1. Chromium. We have assumed thatchromium is emitted in its most potentcarcinogenic form, hexavalentchromium. We believe this assumptionis conservative, but reasonable at thistime for the purpose of determiningwhether chromium emissions could posesignificant risk.

Chromium is likely to be emitted ineither the highly carcinogenic,hexavalent state or in the relatively low-toxicity trivalent state. (The dataavailable to EPA at this time areinadequate to classify the trivalentchromium compounds as to theircarcinogenicity.) Although thehexavalent state could be expected toresult from combustion because itrepresents the more oxidized state,some investigators speculate that mostof the chromium is likely to be emittedin the trivalent state given that thehexavalent state is highly reactive and,thus, likely to be reduced to the trivalentstate. However, preliminaryinvestigations 42 indicate that 50 percent

42 US EPA. "Pilot Scale Evaluation of the Fate ofTrace Metals in a Rotary Kiln Incinerator with a

Continued

I II -IL7. 7717B77



or more of chromium emissions fromhazardous waste incinerators can be inthe hexavalent state when chlorinatedwastes are burned. Unfortunately, dataon hexavalent chromium emissions issparse because a reliable emissionssampling and recovery methodology hasonly recently been developed. 43 Thus,the Agency is not able to establish atthis time a reasonable, worst caseassumption for the fraction of chromiumemissions that may be hexavalent, otherthan assuming 100 percent of chromiumemissions are hexavalent. Consequently,the proposed emission controls underunder the Emissions Screening Limitsand Site-Specific Risk Analysisalternative would be based onemissions of total chromium unless theapplicant conducts emissions testingcapable of reliably determining actualchromium emissions in the hexavalentstate (e.g., by using the soon-to-be-validated methodology referencedabove). In such a case, the EmissionsScreening Limits and Site-Specific RiskAnalysis standards would be applied tothe measured hexavalent chromiumemissions. (The Feed Rate ScreeningLimits, however, would apply to thetotal chromium present in the wastebecause emissions testing is not used tocomply with these limits.)

As additional data become availableon the health effects of chromiumemissions from combustion sources, theAgency will consider what, if any,amendments would be appropriate tothe rule proposed today. For example, ifadditional data indicate that hexavalentchromium emissions invariably accountfor less than 75 percent of totalchromium emissions, the ScreeningLimits could be adjusted accordingly(i.e., by increasing them by 25 percent).The Agency specifically requests data(using validated procedures)documenting hexavalent chromiumemissions from incinerators burninghazardous waste.

2. Nickel. Nickel carbonyl and nickelsubsulfide are suspected humancarcinogens. The Agency is continuingto study other nickel compounds withrespect to carcinogenic potency. Giventhat neither nickel carbonyl nor nickelsubsulfide is likely to be emitted from aconventional incinerator because of the

Venturi Scrubber/Packed Column Scrubber, Vol. 1,Technical Results", April 1989.

43 Steinsberger, S. C. and Carver, A. C., EntropyEnvironmentalists, Inc., and Knoll J. E., at al, USEPA, "Sampling and Analytical Methodology forMeasurement of Low Levels of HexavalentChromium from Stationary Sources", Paperpresented at EPA/AWMA Symposium at Raleigh.N. C., May 1989, as revised by draft datedNovember 10, 1989. entitled "Method Cr*6- -

Determination of Hexavalent Chromium EmissionsFrom Stationary Sources".

highly oxidizing environment, we arenot proposing controls for nickel. If theAgency determines that nickelcompounds in the oxidized state may behuman carcinogens or that nickelcarbonyl or nickel subsulfide could, infact, be emitted from some incinerators,we will propose to control thosecompounds. We note however, that weare proposing today to include twoinnovative types of incinerators--infrared and plasma arc-in thedefinition of incinerator. These devicesmay not use oxidation to thermally 'destruct organic compounds and, thus,could conceivably emit nickel inreduced species such as carbonyl andsubsulfide. Given that we do not havefully developed and validated samplingand analysis procedures specifically forthese compounds, we would have toassume conservatively that any nickelemitted from these devices wascarbonyl or subsulfide. We specificallyrequest comment on whether thesenoncombustion incinerators are likely to.emit significant levels of nickel carbonylor subsulfide. If so, we also requestinformation on the availability ofvalidated sampling and analysisprocedures for these compounds.

3. Selenium. At the present time, theAgency does not have the health effectsdata needed to establish acceptableambient levels for selenium. At suchtime that health effects data becomeavailable, selenium emissions will becontrolled, if warranted.4

4

C. Metals Emissions Standards45

The metals emissions standardsrequire site-specific risk assessment todemonstrate that metals emissions willnot: (1) result in exceedances of thereference air concentrations (RACs) fornoncarcinogens at the potential MEI;and (2) result in an aggregate increasedlifetime cancer risk to the potential MEIof greater than 1X 10- 5 4- As discussedabove, the RACs for noncarcinogensand risk specific doses (RSDs) forcarcinogens are presented in AppendixH of the boiler/furnace supplementalnotice. See 54 FR 43763 (October 26,1989).

To reduce the burden on applicantsand permitting officials, EPA has

44 Memo from Reva Rubenstein, Chief, HealthAssessment Section, Technical Assessment Branchto Bob Holloway. Chief Combustion Section. WasteTreatment Branch. EPA, entitled "HydrogenBromide, Hydrogen Fluoride. Selenium, and Lead,"October 1, 1987.

46 This discussion has been taken virtuallyverbatim from the October 26,1989 boiler/furnacesupplemental notice (see 54 FR 43758-60).

46 In selecting a risk threshold of 10- for theserules. EPA considered risk thresholds in the range of10- ' to 10- t As discussed in Section LD. of PartThree of the text, the Agency requests comment onalternative risk thresholds.

developed conservative ScreeningLimits for metals emissions (and feedrates) as a function of terrain adjustedeffective stack height, terrain, and landuse. See discussion below. If theScreening Limits are not exceeded, site-specific dispersion modeling would notbe required to demonstrate conformancewith-the proposed standard.

If the Screening Limits are exceeded,the applicant would be required toconduct site-specific dispersionmodeling in conformance with"Guideline on Air Quality Models(Revised)" (1986), and Supplement A(1987), EPA Publication Number 450/2-78-027R, available from NationalTechnical Information Service,Springfield, Virginia, Order Nos. PB 86--245280 and P188-150958. We areproposing to incorporate that documentby reference in § 270.6(a).

The use of physical stack height inexcess of Good Engineering Practice(GEP) stack height is prohibited in thedevelopment of emission limitationsunder EPA's Air Program at 40 CFR51.12 and 40 CFR 51.18. We propose toadopt a similar policy by limiting theheight of the physical stack for whichcredit will be allowed in complying withthe metals (and other) standards (i.e.,both site-specific dispersion modelingand Screening Limits). GEP identifies theminimum stack height at whichsignificant adverse aerodynamic effectsare avoided. Although higher than GEPstack heights are not prohibited, creditwill not be allowed for stack heightsgreater than GEP. Good EngineeringPractice (GEP) maximum stack heightmeans the greater of: (1) 65 meters,measured from the ground-levelelevation at the base of the stack; or (2)Hg=H+1.5L 4 7

where:Hg=GEP minimum stack height measured

from the ground-level elevation at thebase of the stack;

H=heiht of nearby structure(s) measuredfrom the ground-level elevation at thebase of the stack;

L=lesser dimension, height or projectedwidth, of nearby structure(s).

If the result of the above equation isless than 65 meters, then the actualphysical stack height, up to 65 meters,could be used for compliance purposes.If the result of the equation is greaterthan 65 meters, the physical stack heightconsidered for compliance purposescannot exceed that level.

4 "We note that this equation also identifies theGEP minimum stack height necessary to avoidbuilding wake effects. EPA recommends theapplication of GEP to define minimum stack heightsto minimize potentially high concentration ofpollutants in the immediate vicinity of the unit.

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EPA requests comment on this use ofGEP maximum stack height. We notethat although an owner or operatorcould increase his physical stack heightup to the GEP maximum to achievebetter dispersion and a higher allowableemission rate he should first considerthat that EPA plans to establish (afterproposals and opportunity for comment)a best demonstrated technology (BDT)particulate standard that is likely to be0.01 to 0.22 gr/dscf. Thus, he would bemore likely to upgade his emissioncontrol equipment to state-of-the-artcontrol rather than increase stackheight.

EPA specifically requests commentson how many facilities are likely toexceed the Screening Limits discussedbelow and, thus, would conduct site-specific dispersion modeling to' complywith the proposed rule. Further, werequest information on the changes toequipment and operations that would berequired to comply with the ScreeningLimits if the provision for site-specificdispersion modeling was not available.

D. Screening Limits

EPA developed conservativeScreening Limits for metals emissionrates (and feed rates] to minimize theneed for site-specific dispersionmodeling, and thus, reduce the burdenon applicants and permitting.46 TheScreening Limits are provided as afunction of terrain-adjusted effectivestack height, terrain, and urban/ruralclassification as discussed below, TheScreening Limits would be included inthe "Risk Assessment Guideline for

48 We note that the Screening Limits are designedto be conservative and would likely limit emissionsby a factor of 2 to 20 times lower than would beallowed by site-specific dispersion modeling.

Permitting Hazardous Waste ThermalTreatment Services" (RAG) whichwould be incorporated by reference inthe rule at § 270.6. See section I.H ofpart Three for a discussion of the RAG.

The Screening Limits proposed todayfor incinerators are identical to thoseproposed for boilers and industrialfurnaces in the October 26, 1989supplemental notice. See 54 FR 43758-62(appendices F and G) for discussion ofthe derivation and implementation ofthe Limits and pages 43745-51 (appendixE) where the Limits are presented. Weare not repeating that information intoday's notice.

IH. Proposed Controls for Emissions ofHydrogen Chloride

A. Summary of Existing Standard

Highly-chlorinated wastes from themanufacturing of organic chemicals,highly-chlorinated spent solvents, andsolvent recovery distillation bottoms areroutinely incinerated in hazardouswaste incinerators. Chlorine inhazardous waste produces hydrochloricacid (1I) upon combustion, which cancause serious health hazards if it is notremoved with flue gas cleaningequipment such as wet scrubbers.(Other halogens of potential healthconcern such as fluorine and bromineare also common constituents inhazardous waste. However, EPA doesnot have adequate health data uponwhich to base a regulation at this time.When data becomes available, EPAintends to revise the regulation toinclude other halogens if we determinethat they can pose unacceptable healthrisks. 49

40 Memo from Reva Rubenstein, Chief,,HealthAssessment Section, Technical Assessment Branchto Bob Holloway, Chief. Combustion Section, Waste

Under EPA's existing rules, anincinerator burning hazardous wastemust control HCl emissions to the largerof either 1.8 kilograms (4 pounds) perhour or 1 percent of the HCl in the stackgas prior to entering any pollutioncontrol equipment. This performancestandard at § 264.343 (b) is based on thecapability of wet scrubbers to removeacid gas, with the expectation that theindustrial threshold limit value forhydrogen chloride would rarely, if ever,be exceeded.

B. The Existing Standard.May Not BeFully Protective in Certain Situations

Risk assessment using reasonable,worst-case facilities discussedpreviously indicates that'incineration ofhazardous waste with total chlorinelevels of 35 percent (350,000 ppm) canpose exceedances of the HCl short termreference air concentations (RACs) evenwhen 99 percent of HCl emissions areassumed to be removed from the stackgas as currently required by'§ 264.343(b). See Table 3. Long term (i.e.,annual) reference air concentations,however, are not likely to be exceeded.In addition the de minimis HC1 emissionrate that triggers the 99 percent removalrequirement, 4 lb/hr, may not provideadequate protection. See table E-9 ofappendix E in the boiler furnacesupplement notice (54 FR 43751)indicating that when terrain adjustedeffective, stack height is less than 30 m innoncomplex terrain and 50 m in complexterrain, a 41b/hr emission rate couldresult in an exceedance of the short-term RAC.

Treatment Branch, EPA, entitled "HydrogenBromide, Hydrogen Fluoride, Selenium, and Lead,"October16,1987.

TABLE 3.-MAXMUM CONCENTRATIONS OF HCI FOR SELECTED WORST-CASE FACILITIES

Dispersion coefficient Dispersion coefficient c lb/hr Ambient conc. p.g/ Ambient conc. ;Lg/ Risk ambient/RAC 3 Risk ambient/RACpg/m3Igfsec 3 . apacity bh

minute 3 pg/m3/g/sec annual m3 3 minute m3 annual minute annual

639.04 8.85 600 169.09 2.34 1.13 0.16604.07 10.48 820 218.44 3.79 1.46 0.25264.92 3.32 2920 341.14 4.28 2.27 0.29170.44 2.72 3241 243.61 3.89 1.62 0.26

The RAC for annual exposure to HClis 7 pg/m 3 50 and is based on thethreshold of respiratory effects.Background levels were considered to

50 Memo dated May 4, 1989. from Mike Dourson,EPA Office of Health and Environmentalassessment, to the RID Workgroup, entitled 'Rf.Meeting of February 16, 1989".

be insignificant given that there are notmany large sources of HCl and that thispollutant generally should not betransported over long distances in thelower atmosphere. The RAC for 3-minute exposures is 150 )g/m 3.51

51 Memo from Lisa Ratcliff, EPA, to DwightHilustick, EPA, entitled "Short-term Health-basedNumber for Hydrogen Chloride," Sept. 15, 198.

C. Request for Comment on Controls forFree Chlorine

We noted in the proposed boiler/furnace rules (52 Fr 17008 (May 6, 1987)]that we thought there was a remotepossibility that free chlorine (C12] couldbe emitted from burning chlorinedwastes if there was insufficient

1787917879



hydrogen available (i.e., from otherhydrocarbon compounds or watervapor) to react with all the chlorine inthe waste. We understand, however,that free chlorine emissions have beendetected at a number of hazardouswaste incinerators. Free chlorineemissions are of concern because C12 isa potent irritant to the respiratorysystem. To address this problem, we areproposing today to amend § 264.343(b)so that the existing 99% removalstandard would apply to both HCI andC12.This standard could be met byproviding more hydrogen in the waste orsupplementary fuel or the addition ofsuperheated steam to the stack gas. Inaddition, as with HCI, we are proposingto require a health-based check toensure that the technology-basedstandard is protective. Thus, theapplicant would be required todemonstrate that the maximum exposedindividual (MEI) is not exposed to C12concentrations exceeding the proposedannual average reference airconcentration (RAC) of 0.4 pg/m 3.52 Asfor HCI, the RAC is based on 100% of theinterim inhalation RfD because othersources of C12 are expected to havelittle or no effect on background levelsdue to the short life of C12 in theatmosphere.

As with the HCI standards,compliance with the health-based Cl2standard would be domonstrated by: (1)emissions testing and dispersionmodeling;, (2) emissions testing andconformance with C12 emissionsScreening Limits; or (3) waste analysisand conformance with chlorine feed rateScreening Limits. The C12 ScreeningLimits would be developed using thesame methodology used for the metalsLimits (e.g., same dispersion or dilutionfactors; feed rate limits assume allchlorine on the feed is emitted as C12).(The dispersion factors used to establishthe HCI Screening Limits were not usedbecause they are based on short-term(i.e., 3-minute) exposures. A short-termRAC is not yet available for C12.) Giventhat the RAC for C12 is 1.33 times theRAC for mercury, the Screening Limitsfor C12 would be 1.33 times the Limitsestablished for mercury in Appendix Eof the boiler/furnace supplementalnotice. See 54 FR 43745 (October 26,1989).

D. Basis for Proposed StandardsThe basis for the proposed standards

HCI standards for incinerators isidentical to that proposed for boilers

52 Memo from Priscilla Halloran, EPA, to DwightHlustick, EPA. enititled "Health-Based AirConcentrations'for Chlorine and N-nitroso-n-methyluera", dated January 4, 1990.

and furnaces as discussed in theOctober 26, 1989, supplemental notice.In addition, the implementation of thecontrols and the controls themselves(i.e., compliance with feed rate oremission rate Screening Limits, ordemonstration by site-specificdispersion modeling that the RAC is notexceeded at the MEI) would be identicalfor boilers/furnaces and incinerators.See Appendices, E, F, and G of thesupplemental notice at 54 FR 43751-62.Those discussions and information arenot repeated here, but are to beconsidered fully applicable.

IV. Proposed Controls for Emissions ofProducts of Incomplete Combustion

A. Hazard Posed by Emissions ofProducts of Incomplete Combustion(PICs)

The burning of hazardous wastecontaining toxic organic compoundslisted in Appendix VIII of 40 CFR part261 under poor combustion conditionscan result in substantial emissions ofcompounds that result from theincomplete combustion of constituentsin the waste, as well as emissions of theoriginal compounds which were notburned. The quantity of toxic organiccompounds emitted depends on theconcentration of the compounds in thewaste, and the combustion conditionsunder which the waste is burned.

Data on typical PIC emissions fromhazardous waste combustion sourceswere compiled and assessed in recentEPA studies.5 3

54 These studiesidentified 37 individual compounds inthe stack gas of the eight full-scalehazardous waste incinerators tested, outof which 17 were volatile compoundsand 20 semivolatile compounds. Eightvolatile compounds (benzene, toluene,chloroform, trichloroethylene, carbontetrachloride, tetrachloroethylene,chlorobenzene, and methylene chloride),and one semivolatile compound(naphthalene) were identified mostfrequently in over 50 percent of the tests.Some of these compounds arecarcinogenic. It was found that PICemission rates vary widely from site-to-site which may be due, in part, tovariations in waste feed composition

53 Wallace, D. at al., "Products of IncompleteCombustion from Hazardous Waste Combustion."Draft Final Report,'EPA Contract No. 68-03-3241,Acurex Corporation, Subcontractor No. ES 59689A,Work Assignment 5, Midwest Research InstituteProject No. 8371-141), Kansas City, MO, June 1988.

54 Trenholm, A., and C. C. Lee. "Analysis of PICand Total Mass Emissions from an Incinerator,"Proceedings of the Twelfth Annual ResearchSymposium on Land Disposal, Remedial Action,Incineration. and Treatment of Hazardous Waste,Cincinnati. OKL April 21-23,1986, EPA/600-9-86/022. pp. 376-381. August 1986.

and facility size. The median values ofthe nine compounds mentioned aboverange from 0.27 to 5.0 mg/min. Using arepresentative emission rate of 1 mg/min, the stack gas concentration forPICs in a medium-sized facility (250 m3/min combustion gas flow rate) would be4 pg/m a (0.004 pg/l).

The health risk posed by PICemissions depends on the quantity andtoxicity of the individual toxiccomponents of the emissions, and theambient levels to which persons areexposed. Estimates of risk to publichealth resulting from PICs, based onavailable emissions data, indicate thatPIC emissions do not pose significantrisks when incinerators are operatedunder optimum conditions. However,incinerator do not always operate underoptimum conditions. In addition, onlylimited information about PICs isavailable. PIC emissions are composedof thousands of different compounds,some of which are in very minutequantities and cannot be detected andquantified without very elaborate andexpensive sampling and analytical(S&A) techniques. Such elaborate S&Awork is not feasible in trial burns forpermitting purposes and can only bedone in research tests. In addition,reliable S&A procedures simply do notexist for some types of PICs (e.g., water-soluble compounds). The mostcomprehensive analysis of PICemissions from a hazardous wasteincinerator identified and quantifiedonly approximately 70 percent oforganic emissions. Typical research-oriented field tests identify a muchlower fraction-from 1-60 percent. Evenif all the organic compounds emittedcould be quantified, there areinadequate health effects data availableto assess the resultant health risk. EPAbelieves that, due to the abovelimitations, additional testing will not, inthe foreseeable future, be able to provequantitatively whether PICs do or do notpose unacceptable health risk.Considering the uncertainties about PICemissions and their potential risk topublic health, it is therefore prudent torequire that incinerators operate at ahigh combustion efficiency to minimizePIC emissions. Given that carbonmonoxide (CO) is the best availableindicator of combustion efficiency, anda conservative indicator of combustionupset, we are proposing to limit the fluegas CO levels to levels that ensure PICemissions are not likely to poseunacceptable health risk. In cases whereCO emissions exceed a proposed deminimis limit, higher CO levels wouldbe allowed under two alternativeapproaches: (1) if hydrocarbon (HC)

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concentrations in the stack gas do notexceed a good operating practice-basedlimit of 20 ppmv; or (2) if the applicantdemonstrates that HC emissions are notlikely to pose unacceptable health riskusing conservative, prescribed riskassessment procedures. Although weprefer the technology-based approachfor reasons discussed below, we arerequesting comment on the health-basedalternative as well.

B. Existing Regulatory ControlsSection 264.345 of the existing

regulations requires that the permit mustlimit the CO level in the stack exhaustgas based on the trial burn whendemonstrating conformance with thedestruction and removal efficiency(DRE) standard for principal organichazardous constituents (POHCs).Section 264.347 requires that COemissions be monitored continuously ata point downstream of the combustionzone and prior to release to theatmosphere; and § 264.345 requires thatthe incinerator must be equipped with afunctioning system to cut off the wastefeed automatically when the CO limit isexceeded. Thus, the existing regulationsdo not specify an upper limit for CO, butrather limit CO to the levels that occurduring the trial burn. The regulations donot specify limits for PIC emissions norrequire analysis of risks from suchemissions. PICs are assumed to becontrolled by the DRE standard forPOHCs. Although CO levels may oftenbe at levels that represent highcombustion efficiency (e.g., below 100ppmv, the de minimis limit proposedtoday) when demonstratingconformance with the DRE standard,there is no assurance that such low COlevels will always occur. Test dataindicate that 99.99 percent DRE can beachieved when incinerators (and boilersand industrial furnaces) are operatingunder upset combustion conditions asevidenced by high CO stack gas levelsand even smoke. Apparently, organicconstituents in the waste are readilydestroyed in the flame zone, butcombustion by-products or PICs may notbe exposed to adequate time,temperature, and turbulence to bereduced to low levels. Thus, existingregulatory provisions may not beadequate to ensure that PICs do notpose unacceptable risk.C. Basis for CO Standards

EPA is proposing to limit flue gascarbon monoxide levels to ensure thatincinerators that burn hazardous wasteoperate at high combustion efficiency toreduce the potential risk from'emissionsof PICs. EPA believes that a CO level of100 ppmv represents high combustion

efficiency operations that wouldvirtually ensure that PIC emissions arelimited to levels that pose acceptablerisk to public health. However, allincinerators (e.g., those that handlecontainers of volatile waste or that havefluid beds) may not be able to readilymeet a 100 ppmv CO limit. Because wehave not been able to establish a directcorrelation between CO, PIC emissions,and the resulting health risk (i.e., whenCO is 150 or 200 ppmv we are uncertainif PIC emissions are likely to posesignificant risk), we are proposing anapproach to waive the CO limit of 100ppmv. Under the waiver, any CO levelachieved during the DRE trial bumwould be allowed provided thatemissions of hydrocarbons (HC) do notexceed acceptable levels.

1. Summary of Proposed Controls.EPA is proposing a two-tiered approachto control PICs by limiting stack of gasCO levels. The first tier requirescompliance with a CO limit of 100 ppmvon an hourly rolling average 55 basis. Ifa facility meets this CO level, during thetiial bum, 100 ppmv will be the permitlimit. If this CO limit cannot be met, thefacility could operate at higherpermitted CO levels under a Tier IIwaiver. The 100 ppmv CO limit wouldbe waived under two alternativeapproaches: (1) a demonstration thathydrocarbon (HC) emissions are notlikely to pose unacceptable health riskusing conservative, prescribed riskassessment procedures; or (2) atechnology-based demonstration thatthe HC concentration in the stack gasdoes not exceed a good operatingpractice-based limit of 20 ppmv.Although we prefer the technology-based approach for reasons discussedbelow, we request comment on thehealth- based alternative as well.

The CO limits for either Tier I or TierII must be corrected to dry stack gas and7 percent oxygen in the stack gas. Thecorrection to dry gas is necessary onlyfor instruments that measure CO on awet basis. This correction factor forhumidity would initially be determinedduring the trial bum and annuallythereafter unless specified otherwise inthe permit. The oxygen correction factormust be determined at intervalsspecified in the permit (not lessfrequently than annually). The oxygenand humidity correction factors wouldbe applied continuously. (The basis forthe 7 percent oxygen correction factor isdiscussed in section IV, C.4 below.)

.The existing regulations alreadyrequire that the hazardous waste feed

5 An hourly rolling average is the arithmeticmean of the 60 most recent 1-minute average valuesrecorded by the continuous monitoring system.

must be cutoff automatically when thepermitted CO limits are exceeded.Today's proposal adds a requirementthat hazardous waste burning may beresumed when CO levels are broughtwithin the permitted limits. When thehazardous waste feed is cut off,combustion chamber temperaturesspecified in the permit and the airpollution control equipment functionsmust be maintained as long as anywaste remains in the combustionchamber. For incinerators with asecondary combustion chamber, werequest comment on whethertemperatures should be maintained inboth the primary and secondarychambers to control organic emissionswhen the waste feed is cutoff. Auxiliaryfuels used to maintain temperaturesmust not contain hazardous waste otherthan waste exempt from the substantiverequirements of subpart 0 underprovisions of § 264.340(b).

EPA specifically requests comment onhow to apply the requirement tomaintain temperature following a wastefeed cutoff, as well as other standardsproposed today, to batch incinerators.

2. Use of CO Limits to Ensure GoodCombustion Conditions. By definition,low CO flue gas levels are indicative ofan incinerator (or any combustiondevice) operating at high combustionefficiency. Operating at high combustionefficiency helps ensure minimumemissions of unburned (or incompletelyburned) organics.5 6 In a simplified viewof combustion of hazardous waste, thefirst stage is immediate thermaldecomposition of the POHCs in theflame to form other, usually smaller,compounds, also referred to as PICs.These PICs are generally rapidlydecomposed to form CO.

The secondstage of combustioninvolves the oxidation of CO to CO2(carbon dioxide). The CO to CO2 step isthe slowest (rate controlling) step in thecombustion process because CO isconsidered to be more thermally stable(difficult to oxidize) than otherintermediate products of combustion ofhazardous waste constituents. Since fuelis being fired continuously, bothcombustion stages are occurringsimultaneously.

56 Given that CO is a gross indicator ofcombustion performance, limiting CO may notabsolutely minimize PIC emissions. This is becausePICs can result from small pockets within thecombustion zone where adequate time, temperature,and turbulence have not been provided to oxidizecompletely the combustion products of the POHCs.Available data, however, indicate that PICemissidns do not pose significant risk whencombustion devices are operated at' highcombustion efficiency. EPA is conducting additionalfield and pilot scale testing to address this issue.

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Using this view of waste combustion,CO flue gas levels cannot be correlatedto DRE for POHCs and may notcorrelate well with PIC destruction. Asdiscussed below, test data show nocorrelation between CO and DRE, butdo show a slight apparent correlationbetween CO and chlorinated PICs, and afair correlation between CO and totalunburned hydrocarbons. Low CO is anindicator of the status of the CO to CO2conversion process, the last, rate-limiting oxidation process. Sinceoxidation of CO to CO2 occurs afterdestruction of the POHC and its (other)intermediates (PICs), the absence of COis a useful indication of POHC and PICdestruction. The presence of high levelsof CO in the flue gas is a usefulindication of inefficient combustion and,at some level of elevated CO flue gasconcentration, an indication of failure ofthe PIC and POHC destruction process.We believe it is necessary to limit COlevels to levels indicative of highcombustion efficiency because we donot know the precise CO level that isindicative of significant failure of thePIC and POHC destruction process. It ispossible that the critical CO level maybe dependent on site-specific and event-specific factors (e.g., fuel type, air-to-fuelratios, rate and extent of change of these

and other factors that affect combustionefficiency). We believe limiting COlevels is prudent because: (1) it is awidely practiced approach to improvingand monitoring combustion efficiency;and (2) most well designed and operatedincinerators can easily be operated inconformance with the proposed Tier ICO limits of 100 ppmv.

The Tier I CO limit proposed todayspecifies a 100 ppmv CO limit in thepermit even though the CO level duringthe trial burn will be lower (i.e., bydefinition, under Tier I). EPA consideredthis issue carefully and the proposal isbased on three considerations. First,DRE will not be reduced below thelevels specified in § 264.343(a)(1) forPOHCs by the proposed CO limits.Second, many incinerators run veryefficiently during a trial bum andindicate less than 10 ppmv of COemissions. It may not be possible toachieve that high degree of efficiency ona consisent basis and specifying suchlow trial bum CO values may result innumerous hazardous waste feed cut-offsdue to CO exceedances. Third, theemission of PICs from incinerators hasnot been shown to increase linearly atsuch low CO levels. In fact, the trialburn data indicate that total organic

emissions are consistently low (i.e., atlevels that pose acceptable health risk)when CO emission levels are less than100 ppmv. Two studies show that nomeasurable change in DRE is likely tooccur for CO levels up to 100 ppmv. Thefirst study generated data fromcombustion of a 12 -component mixturein a bench scale facility.5 7 The COlevels ranged from 15 to 522 ppmvwithout a significant correlation to thedestrdction efficiency for the compoundsinvestigated. The second study wasconducted on a pilot scale combustor.55

Test runs were conducted with averageCO concentrations ranging from 30 to700 ppmv. When the concentration wasless than 220 ppmv no apparentdecrease in DRE was noticed, but higherCO concentrations showed a definitedecrease in DRE. EPA specificallyinvites comments on whether the permitshould limit CO according to trial bumvalues in lieu of the limits specifiedhere.

3. Supporting Information on CO as aSurrogate for PICs. Substantialinformation is available that indicateCO emissions may relate to PICemissions.

Combustion efficiency is directlyrelated to CO by the following equation:

percent C0 2Combustion Efficiency (CE)= percent CO2 + percent CO (100)

CE has been used as a measure ofcompleteness of combustion.5 9 EPA'sregulations for incineration of wastePCBs at 40 CFR 761.70 require thatcombustion efficiency be maintainedabove 99.9 percent. As combinationbecomes less efficient or less complete,at some point, the emission of totalorganics will increase and smoke willeventually result. It is probable thatsome quantity of toxic organiccompounds will be present in theseorganic emissions. Thus, CE or COlevels provide an indication of thepotential for total organic emissions andpossibly toxic PICs. Data are notavailable, however, to correlate thesevariables quantitatively with PICs incombustion processes.

51 Hall D.L at al. "Thermal DecompositionProperties of a Twelve Component OrganicMixture", Hazardous Wastes & HazardousMaterials, VoL 3. No. 4 pp 4431-449.198.

58 Waterland. LR. "Pilot-scale Investigation ofSurrogate Means of Determining POHCDestruction' Final Report for the ChemcialManufacturers' Association. ACUREX CorporationMountain View. California, July 1983.

O We specifically request comments on whether

Several studies have been conductedto evaluate CO monitoring as a methodto measure the performance ofhazardous waste combustion. Thoughcorrelations with destruction efficiencyof POHCs have not been found, the datafrom these studies generally show thatas combustion conditions deteriorate,both CO and total hydrocarbonemissions increase. These data supportthe relation between CO and increasedorganic emissions discussed above. Inone of these studies, 60 an attempt wasmade to correlate the concentrations ofCO with the concentrations of fourcommon PICs (benzene, toluene, carbontetrachloride, and trichloroethylene) instack gases of full scale incinerators. Fora plot of CO versus benzene, one of themost common PICs, there is

combustion efficiency, as defined above in the text(i.e., considering both CO and CO emissions)should be used to control THC emissions ratherthan GO alone.

a0 Trenholm, A.. P. Gorman, and G. Jungclaus."Performance Evaluation of Full-Scale HazardousWaste Incinerators. VoL 2--IncineratorPerformance Results." EPA-600/2-84-l81b, NTISNo. PB 85-129518, November 1984.

considerable scatter in the dataindicating that parameters other thanCO affect the benzene levels. However,there is a trend in the data that suggeststhat when benzene levels are high, COlevels also are high. The converse hasnot been found to be true; when benzenelevels are low, CO levels are not alwayslow. Similar trends were observed fortoluene and carbon tetrachloride, butnot for trichloroethylene. In the pilot-scale study by Waterland cited earlier,similar trends were observed forchlorobenzene and methylene chlorideand in another study 61 similar trendswere observed for total chlorinatedPICs. These data support the conclusionthat when the emission rates of somecommonly identified PICs aresufficiently high, it is likely that COemissions will also be higher thantypical levels.

More importantly, however, availabledata indicate that when CO emissions

61 Chang. D.P. at al., "Evaluation of a Pilot-ScaleCirculating Bed Combustor as a Potenial HazardousWaste Incinerator," APCA Journal, Vol. 37, No. 3,pp. 266-274, March 1987.

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are low (e.g., under 100 ppmv), PICemissions are always low (i.e., at levelsthat pose acceptable health risk]. Theconverse may not be true: when CO ishigh, PIC levels may or may not be high.Thus, the Agency believes that CO is aconservative indicator of potential PICemissions and, given that CO monitoringis already required in the presentregulations, the emission levels shouldbe limited to low levels indicative ofhigh combustion efficiency. (For thosefacilities where CO emissions may behigh but PIC emissions low, we areproviding an opportunity under Tier II ofthe proposed rule to demonstrate that, infact, PIC emissions pose acceptablehealth risks at elevated CO levels.)

D. Derivation of the Tier I CO Limit.

The proposed Tier r de minimis COlimit of 100 ppmv was selected for anumber of reasons: (1) it is within therange of CO levels that represent highcombustion efficiency; (2] available fieldtest data indicate that PICs are notemitted at levels that pose unacceptablerisks when CO does not exceed 100ppmv; (3) the 100 ppmv level isconsistent with the combustionefficiency of 99.9 percent currentlyrequired by EPA's PCB incinerationregulations codified at 40 CFR 761.70; (4]it is the CO limit proposed for boilersand furnaces burning hazardous waste(see 52 FR 16997 (May 6, 1987), and 54FR 43718 (October 26, 1989)); and (5) it isa level that the majority of welldesigned and operated incinerators canmeet. These reasons are discussedbelow.

EPA regulations referred to above (40CFR part 761) under the authority of theToxic Substance Control Act (TSCA) forthe incineration of PCB-laden wastesrequire a minimum combustionefficiency (CE) of 99.9 percent.Combustion efficiency of 99.9 percent,calculated as CO2/(CO2 +CO),translates to CO emissions levels of 80to 125 ppmv corrected to 7 percent 02,depending on the fuel C/H ratio. Theintent of the PCB combustion efficiencyrule is to minimize emissions ofpotentially toxic organics. Therefore, theproposed 100 ppmv CO level forhazardous wastes destruction isconsistent with the intent of theregulations governing the incineration ofPCB wastes.

CO emission data from hazardouswaste incineration research and trialburn tests also confirm the relationshipbetween CE greater than 99.9 percentand CO levels less than 100 ppmv. Thecombustion efficiencies in all caseswhere data were available werecalculated to exceed 99.9 percent,

except for the test runs where COexceeded the proposed CO limit.

The data from the research tests ofeight incinerators cited earlier 62

showed that most incinerators easilycomplied with the 100 ppmv proposedlimit with two exceptions. The first'exception was a maximum hourlyaverage of 120 ppmv which came fromone test run out of four at a test site.Information was not available toevaluate why CO levels were higher forthis test run; however, all the other threeruns at this site showed routinecompliance with the proposed limits.The second exception came from datafor a rotary kiln that was fed containersof volatile waste. All three runs at thissite showed CO levels clearly higherthan the proposed limits. Thisincinerator operated at a relativelyhigher baseline CO level and alsoexhibited frequent CO spikes as drumsof volatile waste were fed to the rotarykiln.

Another data set on CO is containedin the results of trial burn testsconducted during permitting ofhazardous waste incinerators. 63 Basedon an evaluation of these data, weestimate that some incinerators couldfail the proposed CO limits. (Undertoday's proposal, owners and operatorsof these incinerators would be requiredto demonstrate that their HC emissionsare acceptable]. But, in general, the datareviewed suggests that most hazardouswaste incinerators can easily achievethe recommended CO limits.Information was not available toevaluate why the CO levels were higherat some incinerators and not at others.Reduction of these higher CO levels mayinvolve relatively simple. change in somecases, but may require significantchanges in operating conditions in othercases. Comments by incineratoroperators have indicated that certainincinerator operators may havedifficulty achieving the proposed limitswithout a substantial reduction incapacity. The type of operationsspecifically referred to are rotary kilnincinerators that feed containers ofvolatile waste, and fluidized bedincinerators. Volatile hazardous wastewhen batch fed in containers canvolatilize and burn rapidly creating amomentary oxygen deficiency in theprimary combustion chamber. A CO

62 Trenholm, A., P. Gorman, G. Jungclaus,

"Performance Evaluation of Full-Scale HazardousWaste Incinerators, Vol. 2-IncineratorPerformance Results," EPA-800/2-84-181b. NTISNo. PB 85-129518, November 1984.

63 PEI Associates and JACA Corporation. "PermitWriter's Guide to Test Burn Data-HazardousWaste Incineration." USEPA Handbook, EPA/625/6-86/012, September 1986.

spike generally occurs every time acontainer in fed in the system and thecumulative spikes could increase theaverage CO level to go above 100 ppmv.The average CO level is also affected bythe volatility of the waste, the quantityof waste fed in one batch, the frequencyat which batches are fed, and thevolume of the combustion chamber. EPAspecifically requests comments fromincinerator operators about theachievabiity of the Tier I CO limit.Comments should include supporting adocumentation or data on any of theabove issues, including informationdemonstrating how the device isdesigned and operated to achieve highcombustion efficiency but nonethelesshas CO levels exceeding 100 ppmv.

Low flue gas CO concentration iswidely used as an indicator of "goodcombustion practices" for waste-to-energy systems. Combustion ofmunicipal waste and refuse derived fuel(RDF) in modem design municipal wastecombustors (MWCs) requires sufficientoxygen and mixing at uniformly highfurance temperature to ensure completecombustion of toxic organics, includingpolychlorinated dibenzo-p-dioxins andfurans (PCDD/PCDF). Although, by mosttechnical accounts, CO is not considereddirectly relatable to PCDD/PCDFemissions from MWCs, the Agency hasrecently proposed to limit CO levelsfrom MWCs to ensure high combustionefficienty.A4 Limits on CO combinedwith other requirements are designed tominimize emissions of PCDD/PCDFemissions. The proposed MWC COlimits vary from 50 ppmv to 150 ppmvdepending on the type of device, and arecalculated on a 4-hr average basis, dry-corrected to 12 percent CO 2. The limitsare technology-based-they representlevels readily achievable by well-designed and well-operated units. EPAdoes not believe that the proposed limitsof 50 ppmv to 150 ppmv for MWCspresents a conflict with today'sproposed 100 ppmv de minimis COemission limit for hazardous wasteincinerators. The 100 ppmv limitproposed in today's rule for hazardouswaste incinerators can be waived toallow higher CO levels provided that HClevels to not exceed acceptable levels.We did not propose to limit CO to alevel lower than 100 ppmv, althoughreadily achievable by many hazardouswaste incinerators, because availabledata indicate that PIC emissions do notpose significant health risk when the COconcentration is 100 ppmv.

61 See 54 FR 52251 (December 20, 1989).

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E. Derivation of the Tier !! ControlsIf the highest hourly average CO level

during the trial burn exceeds the Tier Ilimit of 100 ppmv, a higher CO levelwould be allowed if emissions ofhydrocarbons (HC) are consideredacceptable under two alternativeapproaches: a health-based approach, ora technology-based approach. We preferthe technology-based approach forreasons discussed below. One of thealternatives will be selected for the finalrule based on public comment andAgency evaluation, including a critiqueby the Agency's Science Advisory Board(SAB). e5

1. J-Ieolth-Based Approach. Under thehealth-based approach to waive the 100ppmv CO limit, the applicant would beallowed to demonstrate that PICemissions from the combustion devicepose an acceptable risk (i.e., less than10 -

566) to the maximum exposedindividual (MEI). Under this approach,we would require the applicant toquantify total hydrocarbon (THC)emissions during the trial burn and toassume that all hydrocarbons arecarcinogenic compounds with a unit riskthat has been calculated based onavailable data. The THC unit risk valuewould be 1.0 x 10-5 m3/Ag andrepresents the adjusted, 95th percentileweighted (i.e., by emissionconcentration) average unit risk of allthe hydrocarbon emissions data in ourdata base of field testing of boilers,industrial furnaces, and incineratorsburning hazardous waste. The weightedunit risk value for THC considers,emissions data for carcinogenic PICs(e.g., chlorinated dioxins and furans,benzene, chloroform, carbontetrachloride) as well as data for PICsthat are not suspected carcinogens andare considered to be relatively nontoxic(e.g., methane, and other C, as well asC2 pure hydrocarbons, i.e., containingonly carbon and hydrogen). We adjustedthe data base as follows to increase theconservatism of the calculated THC unitrisk value: (1) we assumed that thecarcinogen formaldehyde is emittedfrom hazardous waste combustiondevices at the 95th percentile levelsfound to be emitted from municipalwaste combustors; 67 and (2) we

e5 Report of the Products of IncompleteCombustion Subcommittee. ScienceAdvisoryBoard. U.S. EPA. "Review of the Office of SolidWaste Proposed Controls for Hazardous WasteIncinerators: Products of Incomplete Combustion",October 24. 1989.

e0 In selecting a risk threshold of 10 - 5 for these

rules, kDA considered risk thresholds in the rangeof 10 - 1 to 10-. As discussed in section I.D. of PartThree of the text, the Agency requests comment onalternative risk thresholds.

6" Because of its extremely high volatility, specialtask sampling and analysis procedures are required

assumed that every carcinogeniccompound in appendix VIII of part 261for which we have health effects databut no emissions data is actuallyemitted at the level of detection of thetest methods, 0.1 -qg/1. Finally, weassigned a unit risk of zero tononcarcinogenic compounds (e.g., C-C.hydrocarbons such as methane,acetylene). The calculated unit riskvalue for TIC is I x 10-5 m/pg,comparable to the value for carbontetrachloride. 6

To implement the health-basedapproach with minimum burden onpermit writers and applicants, we haveestablished conservative THC emissionScreening Limits as a function ofeffective stack height, terrain, and landuse. See Appendix B of the October 20,1989, supplemental notice for boilers/furnaces (54 FR 43739). These ScreeningLimits were back-calculated from theacceptable ambient level for THC, 1.0pg/m s (based on the unit risk valuediscussed above and an acceptable MEIrisk of 10-5, using conservativedispersion coefficients. (We also usedthose dispersion coefficients to developalternative emissions and feed ratelimits for metals and HCI, as discussedelsewhere. The basis for thosedispersion coefficients is also discussedelsewhere.) If THC emissions measuredduring the trial burn do not exceed theTHC emissions Screening Limits, the riskposed by THC emissions would beconsidered acceptable. If the ScreeningLimits are exceeded, the applicantwould be required to conduct site-specific dispersion modeling using EPA's"Guideline on Air Quality Models(Revised)" to demonstrate that the(potential) MEI exposure level (i.e., themaximum annual average ground levelconcentration) does not exceed theacceptable THC ambient level.

2. Technology-Based Approach. Underthis Tier II approach, the Tier I CO limitof 100 ppmv would be waived if HClevels in the stack gas do not exceed agood operating practice-based limit of 20ppmv.

We have developed this technology-based approach because of concernabout current scientific limitations of therisk-based approach. In addition, therisk-based approach could allow THClevels of several hundred ppmv-levelsthat are clearly indicative of upsetcombustion conditions.

to measure formaldehyde emissions. Such testinghas not been successfully conducted during EPA'sfield testing of hazardous waste combustiondevices.

68 For additional technical support, see U.S. EPA,"Background Information Document for theDevelopment of Regulations for PIC Emissions fromHazardous Waste Incinerators." October 1989(Draft Final Report).

The Agency believes that riskassessment can and should be used tolimit the application of technology-based controls-that is, to demonstratethat additional technological controls,even though available, may not beneeded. However, we are sufficientlyconcerned that our proposed to THCrisk assessment methodology may havelimitations, particularly when applied toTHC emitted during poor combustionconditions (i.e., situations where COexceeds 100 ppmv), that we areconsidering a cap on HC emissions.Although we believe the development ofrisk-based approach is a positive step,we are concerned whether the risk-based approach is adequately protectivegiven our limited data base on PICemissions and understanding of whatfraction of organic emissions would bedetected by the HC monitoring system.Notwithstanding the limitations of theTHC risk assessment methodology,however, we believe it is reasonable touse the methodology to predict whethera technology-based limit appears to beprotective. We have used the riskassessment methodology to show that a20 ppmv HC limit appears to beprotective of public health.

We discuss below our concerns withthe proposed THC risk-based approachand the basis for tenatively selecting 20ppmv as the recommended HC limit(measured with a conditioned gasmonitoring system, recorded on anhourly average basis, reported aspropane, and corrected to 7% oxygen).

a. Concerns with the THC RiskAssessment Methodology. Our primaryconcern with the risk assessmentmethodology is that, although it may bea reasonable approach for evaluatingPIC emissions under good Combustionconditions, it may not be adequate forpoor combustion conditions-when COexceeds 100 ppmv. The vast majority ofour data on the types andconcentrations of PIC emissions fromincinerators, boilers, and industrialfurnaces burning hazardous waste wereobtained during test burns when thedevices were operated under goodcombustion conditions. CO levels wereoften below 50 ppmv. Under Tier IIapplications, CO levels can be 500 to10,000 ppmv or higher (there is no upperlimit on CO).69 The concern is that wedo not know whether the types andconcentrations of PICs at these elevatedCO levels, indicative of combustionupset conditions, are similar to the typesand concentrations of PICs in our database. It could be hypotesized that as

e9 Hazardous waste incenerators have operatedat CO levels exceeding 13,000 ppmv during trialburns that achieved 99.99% distributed and removalefficiency.

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combustion conditions deteriorate, theratio of semi-and nonvolatilecompounds to volatile compounds mayincrease. If so, this could have seriousimpacts on the proposed riskassessment methodology. First, theproposed generic unit risk value for THCmay be understated when applied toTHC emitted under poor combustionconditions. This is because semi- andnonvolatile compounds comprise only1% of the mass of THC in our data base,but pose 80% of the estimated cancerrisk. Thus, if the fraction of semi- andnonvolatile compounds increases underpoor combustion conditions, the cancerrisk posed by the compounds may alsoincrease.

To put this concern in perspective, wenote that the proposed THC risk valuecalculated from available data is I X10 - 5 m3/jtg. This unit risk is 100 timesgreater (i.e., more potent) than the unitrisk for the quantified PICs with thelowest unit risk (e.g.,tetrachloroethylene), but 1000 timeslower than the risk for PICs such asdibenzoanthracene, and 10,000 to1,000,000 times lower than the unit riskfor various chlorinated dioxins andfurans.

Second, if the fraction of semi- andnonvolatile THC increases under poorcombustion conditions, the fraction ofTHC in the vapor phase when enteringthe THC detector may be lower than the75% assumed when operating undergood combustion conditions.7 0 If so, thecorrection factor for the so-calledmissing mass would be greater than the1.33 factor proposed.

The Agency is currently conductingemissions testing to improve the database in support of the proposed risk-based approach. We are concerned,however, that the testing that isunderway and planned may not provideenough information to support the risk-based approach. In particular, we areconcerned that our stack sampling andanalysis procedures and our healtheffects data base are not adequate tosatisfactorily characterize the healtheffects posed by PICs emitted underpoor combustion conditions.

A final concern with the riskassessment methodology is that it doesnot consider health impacts resultingfrom indirect exposure. As explainedabove, the risk-based standardsproposed today consider human healthimpacts only from direct inhalation.Indirect exposure via uptake. through the

10 See discussions in US EPA, "BackgroundInformation Document for the Development ofRegulations for PiC Emissions from HazardousWaste Incinerators," October 1989. (Draft FinalReport)

food chain, for example, has not beenconsidered because the Agency has notyet developed site-specific proceduresfor quantifying indirect exposureimpacts for purposes of establishingregulatory emission limits.

b. Basis for the HG Limit. We requestcomment on a HC limit of 20 ppmv asrepresentative of a HC leveldistinguishing between good and poorcombustion conditions. Under thisalternative approach, HC would bemonitored continuously during the trialburn, recorded on an hourly averagebasis, reported as ppmv propane, andcorrected to 7% oxygen. (See discussionbelow regarding performancespecifications of the HC monitoringsystem.) We have tentatively selected alevel of 20 ppmv because: (1) it is withinthe range of values reported in our database for hazardous waste incineratorsand boilers and industrial furnacesburning hazardous waste; and (2) thelevel appears to be protective of humanhealth based on risk assessments usingthe proposed methodology for 30incinerators. 7 1

The available data appear to indicatethat the majority of devices can meet aHC limit of 20 ppmv when operatingunder good conditions (i.e., when CO isless than 100 ppmv). It appears, in fact,that many hazardous waste incineratorscan typically achieve HC levels of 5 to10 ppmv when operating generally atlow CO levels. When incinerators emithigher HC levels typically exceed 100ppmv, indicative of poor combustionconditions. As discussed in the October26, 1989, supplemental notice to theboiler/furnace proposed rules, theavailable information on boilers andindustrial furnaces is not quite as clear,however. Athough the data baseindicates that boilers burning hazardouswaste can easily meet a HC limit of 20ppmv, the Agency has obtained data onvarious types of boilers burning varioustypes of fossil fuels (not hazardouswaste) that indicate that HC levels canexceed 20 ppmv when CO levels are lessthan 100 ppmv. See footnote 70. We arereviewing that data and obtainingadditional information to determine ifan alternative limit may be moreappropriate for boilers. We specificallyrequest comment on whether a HCconcentration of 20 ppmv in factrepresents good operating practice forboilers burning hazardous waste as thesole fuel or in combination with otherfuels.

We also request comment on whethera HC concentration of 20 ppmv

' Memorandum from Shiva Garg, EPA, to theDocket. entitled "Supporting Information for a GOP-Based THC Limit", dated October 20, 1988.

represents good operating practice forindustrial furnaces. Preheater andprecalciner cement kilns, for example,may not be able to readily achieve sucha low HC concentration for the samereason that they typically cannotachieve CO levels below 100 ppmv.Normal raw materials such as limestonecan contain trace levels of organicmaterials that oxidize incompletely asthe raw material moves down the kilnfrom the feed end to the hot end wherefuels are normally fired. Clearly, any HC(or CO) resulting from this phenomenonhas nothing to do with combustion ofhazardous waste fuel. Thus, anincinerator and a preheater orprecalciner cement kiln with exactly thesame quality of combustion conditionsmay have very different HC (and CO)levels. We request comment on: (1) thetypes of industrial furnaces for which aHC level 20 ppmv is representative ofgood combustion conditions; (2) whetheralternative HC limits may be moreappropriate for certain industrialfurnaces; and (3) whether an approachto identify a site-specific HC limitrepresentative of good operatingpractices may be feasible (e.g., whereHC levels when burning hazardouswaste would be limited to baseline HClevels without burning hazardouswaste). In support of comments, werequest data on emissions of CO and HCunder baseline and hazardous wasteburning conditions, includingcharacterization of the type andconcentration of individual organiccompounds emitted.

As mentioned previously, some dataon CO and HC levels from industrialboilers burning fossil fuels (nothazardous waste) appear to indicatethat HC levels can far exceed levelsconsidered to be representative of goodcombustion conditions (20 ppmv) eventhough CO levels are less than 100ppmv. See footnote 70. If it appears thatthis situation can, in fact, occur forparticular devices burning particularfuels, we would consider requiring bothCO and HC monitoring for all suchfacilities irrespective of whether COlevels were less than 100 ppmv duringthe trial burn. Thus, under this scenario,the two-tiered CO controls proposedtoday would be replaced with arequirement to continuously monitor COand HC for those particular facilities.We specifically request information onthe types of facilities where HC levelsmay exceed 20 ppmv even though COlevels are less than 100 ppmv, and theneed to continuously monitor HC forthose facilities irrespective of the COlevel achieved during the trial burn.,

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F. Implementation of Tier I and Tier IIPIC Controls

1. Oxygen and Moisture Correction.The CO limits for either format are on adry gas basis and corrected to 7 percentoxygen. The oxygen correctionnormalizes the CO data to a commonbase, recognizing the variation amongthe different technologies as well asmodes of operation using differentquantities of excess air. In-systemleakage, the size of the facility and thetype of waste feed are other factors thatcause oxygen concentration to varywidely in incinerator flue gases. Sevenpercent oxygen was selected as thereference oxygen level because it is inthe middle of the range of normaloxygen levels for hazardous wasteincinerators and it also is the referencelevel for the existing particulatestandard under § 264.343(c). Thecorrection for humidity normalizes theCO data from the different types of COmonitors (e.g., extractive vs. in situ). Ourevaluation indicates that the above twocorrections, when applied, could changethe measured CO levels by a factor oftwo in some cases.

Measured CO levels should becorrected continuously for the amount ofoxygen in the stack gas according to theformula:

14coC=cow x

21-Y

where CO, is this correctedconcentration of CO in the stack gas,COrn is the measured CO concentrationaccording to guidelines specified inAppendixC, and Y is the measuredoxygen concentration on a dry basis inthe stack. Oxygen should be measuredat the same stack location that CO ismeasured.

2. Formats of the CO Limit. The COlimits under Tier I and Tier II would beimplemented under two alternativeformats. The applicant would select thepreferred approach on a case-by-casebasis. Under Format A, CO would bemeasured and recorded as an hourlyrolling average. Under Format B, calledthe time-above-a-limit format, threeparameters would be specified-anever-to-be-exceeded CO limit, and abase CO limit not to be exceeded formore than a specified time in each hour.

In developing these alternativeformats, EPA considered threealternative methods:

" A level never to be exceeded;" A level to be exceeded for an

accumulated specified time within adetermined time frame; and

, An average level over a specifiedtime that is never to be exceeded.

The first alternative is the simplestand requires immediate shutdown of anincinerator when the limit is exceeded,regardless of how long the CO levelsremain high. Short-term CO excursionsor peaks (a few minutes duration) aretypical of incenerator operation and canoccur during routine operations; e.g.,when a burner is adjusted. It is possiblethat during shutdown and start-up, theincinerator may momentarily have highCO emissions. Since the total massemissions under such momentary COexcursions is not high, a never-to-exceedlimit would impede incineratoroperation while providing littlereduction in health risk.'

The second alternative, allowing theCO level to exceed the limit for aspecified accumulative time within adetermined time frame (e.g., x minutes inan hour, solves the problem associatedwith the first alternative. Incineratorswould not be shut down by a single COpeak of high intensity yet they would berestricted from operation with severalshort interval CO peaks, or a single longduration peak.

The third alternative, allowing the COlevel never to exceed an average leveldetermined over a specified time, alsoavoids the problem of shutting off thewaste feed each time an instantaneousCO peak occurs. A time-weightedaverage value (i.e., integrated areaunder the CO peaks over a given timeperiod) also provides a directquantitative measure of mass emissionsof CO. For this reason, the use of arolling average is EPA's preferredformat. A combination of the first andsecond alternatives, with provisions tolimit mass CO emissions per unit time, isalso proposed as an alternative format.This alternative CO format has beenproposed to reduce the cost ofinstrumentation from that required toprovide continuous rolling average COvalues corrected for oxygen. This formatmay be particularly attractive tooperators of small or intermittentlyoperated incinerators. The COmonitoring system needed for the firstalternative requires continuousmeasurement and adjustment of theoxygen correction factor and continuouscomputation of hourly rolling averages.The instrumentation costs of such asystem, consisting of continuous CO andoxygen monitors with back-up systems,a data logger and microprocessor, couldbe up to $91,000 and would requireincreased sophistication and operatingcosts over simpler systems. The onlyinstrumentation needed for thealternative time-above-the-limit formatis a CO monitor and a timer that can

indicate cumulative time of exceedancesin every clock hour, at the end of whichit is recalibrated (manually orelectronically) to restart afresh. Oxygenalso would not have to be measuredcontinuously in this format; instead, anoxygen correction value can bedetermined from operating datacollected during the trial burn.Subsequently, oxygen correction valueswould be determined annually or atmore frequent intervals specified in thefacility permit.7 2 We have not limitedthe use of this alternative CO format toany size .or to any type or class ofincinerators since we consider that thisalternative format provides an equaldegree of control of CO emissions to therolling average format.

The alternative format would requiredual CO levels to be established by thepermit writer, the first as a never toexceedlimit and the second a lowerlimit for cumulative exceedances of nomore than a specified time in an hour.These limits and the time duration ofexceedance shall be established on acase-by-case basis by equating the massemissions (peak areas) in both theformats so that the regulation is equallystringent in both cases. The BackgroundDocument 73 provides the methodologyand mathematical formulae showinghow this can be done.

3. Monitoring CO and Oxygen.Compliance with the Tier I CO limitwould require: (1) continuous monitoringof CO during the trial burn and after thefacilityis permitted; (2) continuousmonitoring of oxygen during the trialburn and, under the 60-minute rollingaverage format, after the facility ispermitted; and (3) measurement ofmoisture during the trial burn andannually (or as specified in the permit)thereafter. Compliance with the Tier IICO limits would require all the Tier Imeasurements and measurement of HCduring the trial burn. Methods formeasurements of CO and oxygen, (andTHC) must be in accordance with the3rd edition of SW-846, as amended. Themethods are summarized in appendix Cof the October 26, 1989, boiler/furnacesupplemental notice (see 54 FR 43739-45), and are discussed in more detail in"Proposed Methods for Stack Emissions

72 We believe that annual determinations of the

oxygen correction factor will be appropriate in mostcases because the concern is whether duct in-leakage has substantially changed over time. Thefact that excess oxygen levels also change withwaste type and feed rate should be considered inestablishing the correction factor initially.

7S US EPA, "Background Information Document

for the Development of Regulations for PICEmissions from Hazardous Waste Incinerators,"October 1989 (Draft Final Report).

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Measurements of CO, 02, THC, HC1, andMetals at Hazardous WasteIncinerators", U.S. EPA, July, 1989 (DraftFinal Report). If compliance with the COstandard is not demonstrated during theDRE trial burn, the CO test burn must beunder conditions identical to the DREtrial burn.

4. Monitoring HC. Under Tier II,hydrocarbons (HC) would be monitoredduring the trial burn to ensure that thehighest hourly average level does notexceed 20 ppmv. We believe thatcontinuous HC monitoring should alsobe required over the life of the permitand an exceedance of the HC limitshould be linked to automatic wastefeed cutoff. This is because at high COlevels (e.g., greater than 100 ppmv) HClevels may or may not be high (e.g.,greater than 20 ppmv). The concern isthat, although HC levels during the trialburn may be less than 20 ppmv whenCO exceeds 100 ppmv, operations overthe life of the permit within the envelopeallowed by the permit conditions mayresult in HC levels exceeding 20 ppmv.This concern was expressed by EPA'sScience Advisory Board during itscritique of the proposed PIC controls inthe spring of 1989. 7 4 EPA specificallyrequests comments over whethercontinuous monitoring of HC should berequired over the life of the permit underTier II.

EPA had developed specifications forHC monitoring (see Appendix D of theOctober 26, 1989 boiler/furnacesupplemental notice (54 FR 43743-45))that would have required heated gassampling lines and a heated flameionization detector (FID) to keep asmuch of the HC in the vapor phase aspossible. EPA reasoned that heatedsampling lines were needed because theFiD can detect HC only in the vaporphase--condensed organic compoundsare not measured. Preliminary results offield testing of a hazardous wasteincinerator conducted in July 1988indicate that detected HC levels were 3to 27 times greater with a heated FIDsystem compared to an unheated systemwhen CO levels ranged from 100 ppmvto 2760 ppmv. 7 5 The total mass ofvolatile, semivolatile, and nonvolatileorganic compounds was also quantifiedduring those tests using the Level I

74 Report of the Products of IncompleteCombustion Subcommittee, Science AdvisoryBoard. U.S. EPA, "Review of the Office of SolidWaste Proposed Controls for Hazardous WasteIncinerators: Products of Incomplete Combustion".October 24,1989.

75 U.S. EPA. "Measurement of Particulates.Metals. and Organics at a Hazardous WasteIncinerator", November, 1988. (Draft Final Report).NTIS order number. PB 89-23066&

screening procedure. 75 The resultsindicate that the HC levels detected byan unheated FID were much lower thanthe levels determined by the Level Iscreening procedure.

Based on cursor discussions inOctober of 1988 with several hazardouswaste incinerator operators, we hadbelieved that such heated systems werein use at some facilities. A follow-upwritten survey 77 indicated, however,that all of the six incinerator facilitiessurveyed that use a FID to monitor HCused a system that incorporated gasconditioning--condensate trapsaccompanying gas cooling systems.Thus, the Agency has not been able todocument operating experiences with aheated (i.e., not conditioned) gassampling system. Further, weunderstand that based on EPA testsusing a heated FID at an incinerator (seefootnote 66) and comments made duringthe SAB review of the PIC controls, a'heated FID system can pose a number ofproblems: (1) the sample extraction linesmay plug due to heavy particulateloadings and condensate organiccompounds; and (2) semi andnonvolatile compounds may adsorb onthe inside of the extraction lines causingunknown effects on measurements.

Given these concerns about thetechnical feasibility of requiring the useof heated FIDs at this time, we areproposing that gas conditioning beallowed. Such conditioning couldinvolve gas cooling at the condensatetrap to a level between 40 and 64 *F toreduce the moisture content of thesample gas entering the FID to less than2 percent. To reduce operation andmaintenance problems, the samplinglines and FID should probably still beheated. The sample gas cannot,however, be "bubbled" through a watercolumn because this could removewater-soluble hydrocarbons. Wespecifically request comments onperformance specifications for gasconditioning systems.

Allowing-gas conditioning in theinterim until unconditioned systems canbe shown to be practicable virtuallyprecludes the use of the health-basedalternative to assess HC emissionsunder the Tier U controls. This isbecause a large, undetermined fractionof hydrocarbon emissions will becondensed to the trap and will not be

76 The Level of Screening procedure is describedin IEL-RTP Procedure Manual: Level I-Environmental Assessmen 2nid Edition. October1978 (EPA 800/7-78-201). That procedure usesgravimetric and total chromatographical organicprocedures to quantify the mass of semi andnonvolatile organic compounds.

77 U.S. EPA. "THC Monitor Survey". June, 1989(Draft Final Report).

reported by the FID. This is anotherreason that the Agency prefers thetechnology-based, 20 ppmv limit onhydrocarbons as the Tier II standard.

Although a FID system monitoring aconditioned gas will detect only thevolatile fraction of organiccompounds, 78 the Agency believes thisis adequate for the purpose ofdetermining whether the facility isoperating under good operatingconditions. 79 Available data indicatethat when emissions of semi andnonvolatile organic compoundsincrease, volatile compounds alsoincrease.80 Thus, volatile compoundsappear to be a good indicator for thesemi and nonvolatile compounds thatare often of greater concern because oftheir health effects. Given, however, thatthe good operating practice-basedhydrocarbon limit of 20 ppmv was basedprimarily on test bum data using heated(i.e., unconditioned gas) FID systems,"'the Agency considered whether to lowerthe recommended hydrocarbon limitwhen an unheated system is used forcompliance monitoring. As discussedabove, limited available field test dataindicated that a heated system woulddetect two to four times the mass oforganic compounds than a conditionedsystem. We believe, however, that the20 ppmv hydrocarbon limit is stillappropriate when a conditioned systemis used because: (1) the data correlatingheated vs conditioned systems are verylimited; (2) the data on HC emissions arelimited (and there apparently isconfusion in some cases as to whetherthe data were taken with a heated orconditioned system); and (3) the riskmethodology is not sophisticated enoughto demonstrate that a HC limit of 5 or 10ppmv using a conditioned system rather

78 We also note that some of the water-solublehydrocarbons may also be removed by the gasconditioning system.

79 We request comment on whether It would bepracticable to develop a site-specific correctionfactor for monitoring with a conditioned gas systemby monitoring with an unconditioned system as wellduring the trial burn. The ratio of the unconditionedsystem THC level to the conditioned system THClevel could then be used to correct the conditionedsystem THC values over the life of the permit. Thisapproach may not be practicable, however, forreasons including the fact that the waste burnedduring the trial burn for some facilities (e.g.,facilities handling multiple wastes) may notrepresent, with respect to THC emissions, the wastethat will be burned over the life of the permit.

8o U.S. EPA. Measurement of Particulates,Metals, and Organics at a Hazardous WasteIncinerator, November, 1988 (Draft Final Report).NTIS Order No. PB89-2308808

S1 Heated systems were often used during trialburns with acceptable results given the shortduration of the tests and the test personnelavailable to handle operational problems.

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than a limit of 20 ppmv is needed toadequately protect public health.

The HC monitoring method proposedin appendix D of the boiler/furnacesupplemental notice (54 FR 43743) willbe modified to allow an unheated,conditioned system and use ofcondensate trap(s) and otherconditioning methods. Performancespecifications for the gas conditioningsystem would be discussed above.

5. Compliance with Tier I CO Limit.There are a number of alternativeapproaches to evaluate CO readingsduring the trial burn to determinecompliance with the 100 ppmv limitincluding: (1) the time-weighted averageCO level (or the average of the hourlyrolling averages); (2) the average of thehighest hourly rolling averages for alltrial burn runs; or (3) the highest hourlyrolling average. The time-weightedaverage alternative provides the lowestCO level that could reasonably be usedto determine compliance, and thehighest hourly rolling averagealternative provides the highest COlevel that could reasonably be used.There may be other reasonablealternatives between these twoextremes in addition to the one listedabove.

We are proposing to use the mostconservative approach to interpret trialburn CO emissions for compliance wtihthe 100 ppmv Tier I limit--the highesthourly rolling average. (This approach isconservative because we are comparingthe trial burn CO level to the maximumCO allowed under Tier 1-100 ppmv.)We believe this conservative approachis reasonable given that compliancewith Tier I allows the applicant to avoidthe Tier 1H requirement to evaluate HCemissions to provide the additionalassurance (or confirmation) that HCemissions do not exceed levelsrepresentative of good operatingpractice.

6. Establishing Permit Limits for COunder Tier IL The alternatives discussedabove for interpreting CO trial burn dataalso apply to specifying the permit limitfor CO under Tier I. For purposes ofspecifying a Tier II CO limit, however,the time-weighted average approachwould be more conservative than thehighest hourly average approachbecause it would result in a lower COlimit. We are proposing theconservative, time-weighted averageapproach for Tier H compliance becausewe are concerned that the highest hourlyaverage approach may not beadequately protective. Although thehighest hourly average (HHA) approachwould be protective in theory becausethe applicant must demonstrate that thehighest hourly average HC emissions do

not exceed good operating practice-based levels, the HHA approach wouldallow the facility to operatecontinuously over the life of the permitat the highest CO levels that occurredduring one hour of the trial bum.

We specifically request comments onhow to interpret trial bum CO data toestablish Tier II CO limits.

7. Compliance with HC Limit of 20ppmv. The alternative approaches fordetermining compliance with the 20ppmv HC limit under Tier II areidentical to those discussed above forcompliance with the Tier I CO limit.Again, we are proposing the mostconservative approach-the highesthourly rolling average HC level duringthe (at a minimum) three test bums mustnot exceed 20 ppmv.

8. Waste Feed Cutoff Requirements.Today's proposal would require cutoff ofthe waste feed if the CO limit isexceeded. In addition, we are requesting.comment on requiring continuousmonitoring of HC. If continuousmonitoring of HC is required, cut off ofthe waste feed would also be required ifthe HC limit is exceeded.

The regulations proposed todayrequire that minimum permittedcombustion temperatures be maintainedafter waste feed cutoff for the durationthat the wastes remain in thecombustion chamber. To comply withthis requirement, the permit mustspecify the minimum combustionchamber temperature occurring duringthe trial burn for devices that may leave.a waste residue in the combustionchamber after waste feed cutoff (e.g.,devices burning wastes that are solids).We believe that PIC emissions from"smoldering" waste remaining in thecombustion chamber should not poseunacceptable health risks provided thatsystem temperatures are maintained.

An uninterruptible auxiliary burner ofadequate capacity may be needed tomaintain the temperature in thecombustion chamber(s) and allowdestruction of the waste materials andassociated combustion gases left in theincineration system after the waste feedis cutoff due to an upset. The safe start-up of the burners using auxiliary fuelrequire approved burner safetymanagement systems for prepurge, post-purge, pilot lights and induced draft fanstarts. If these safety requirementspreclude immediate start-up of auxiliaryfuel burners and such start-up is neededto maintain temperatures (i.e., if thecombustion chamber temperatures dropprecipitously after waste feed is cut-off),the auxiliary fuel may have to be burnedcontinuously on low fire during non-upset conditions. After cutoff, hazardouswaste may not be used as auxiliary fuel

unless the waste is exempt underexisting § 264.340 (b) or (c) from theemissions standards because the wasteis ignitable, corrosive, or reactive andcontains insignificant levels of toxicconstituents.

There is some concern that thisrequirement to maintain temperature inthe combustion chamber after a wastefeed cutoff may not be feasible in allcases (e.g., where the burner cannot bemaintained in close proximity to thecombustible vapor generation pointbecause of an explosion hazard). EPAspecifically requests comments on thisissue, and what alternate approachshould be used to reduce the possibilityof PIC emissions from waste remainingin the chamber after a waste feed cutoff.

We request comment on severalalternative approaches to allow restartof the waste feed: (1) restart after thehourly rolling average no longer exceedsthe permit limit; (2) restart after anarbitrary 10 minute time period toenable the operator to stabilizecombustion conditions; or (3) restartafter the instantaneous CO level meetsthe hourly rolling average limit. Thisthird alternative (i.e., basing restarts onthe instantaneous CO levels) may beappropriate because it may take quite awhile for the hourly rolling average tocome within the permit limit while theevent that caused the exceedance maywell be over even before the CO monitorreports the exceedance. Under thisalternative, the rolling average could be"re-set" when the hazardous waste feedis restarted either by: (1) basing thehourly rolling average on the CO levelfor the first minute after the restart (thesame approach that would be used anytime the waste feed is restarted forreasons other than a CO exceedance); or(2) assuming more conservatively giventhat CO levels may exceed the permitlimit after the waste feed cutoff whileresidues continue to bum, that thehourly rolling average is equivalent tothe permit limit (e.g., 100 ppmv) prior tothe waste feed restart. A finalrefinement to this third alternative ofallowing restarts after instantaneous COlevels fall below the permit limit wouldbe not to reset the rolling average COlevel and to require that theinstantaneous CO level not exceed the(rolling average) permit limit (e.g., 100ppmv) for the period after the restartand until the rolling average falls belowthe permit limit. Again, we specificallyrequest comment on these alternativeapproaches to allow waste feed restarts.

When the automatic waste feed cutoffis triggered by a HC exceedance (i.e., ifthe final rule limits HC levels beyondthe trial burn and requires continuous

IL7888



HC monitoring), we propose to allow arestart only after the hourly rollingaverage HC level has been reduced to 20ppmv. or less. We are not consideringthe options discussed above for restartsafter a CO exceedance given that HC isa better surrogate for toxic organicemissions than CO. Thus, we believethat a more conservative waste feedrestart policy is appropriate after a HCexceedance.

G. Request for Comment on LimitingAPCD Inlet Temperatures

We are requesting comment onwhether to limit the temperature ofstack gas entering a dry emissionscontrol device (e.g., bag house,electrostatic precipitator (ESP)) tominimize formation of chlorinateddibenzodioxin and dibenzofurans (CDD/CDF). The same discussion is presentedabove in the section requesting commenton additional regulatory issuespertaining to boilers and industrialfurnaces burning hazardous waste.

After conducting extensive emissionstesting of municipal waste combustors(MWCs), the Agency has concluded thatCDD/CDF can form on MWC flyash inthe presence of excess oxygen attemperatures in the range of 480 to 750°F.82 Cooling the flue gases andoperating the air pollution control device(APCD) at temperatures below 450 Fhelps minimize the formation of CDD/CDF in the flue gas. Thus, the Agencyhas recently proposed to limit MWCstack gas temperatures at the inlet to theAPCD to 450 O7. See 54 FR 52251(December 20, 1989).

Given that some hazardous wasteincinerators and boilers and industrialfurnaces burning hazardous waste areequipped with dry particulate controldevices, we request comment on theneed to control gas temperatures to 450*F to minimize CDD/CDF formation.Although available data indicate thatCDD/CDF emissions from hazardouswaste combustion devices are muchlower than can be emitted fromMWCs, 8 it may be prudent to limit

02 See US EPA, "Municipal Waste Combustion

Study. Combustion Control of Organic Emissions",EPA/530-SW-87-021C, NTIS Order No. PB87-206090, US EPA, "Municipal Waste CombustionStudy: Flue Gas Cleaning Technology". EPA/530-SW-87-021D. NTIS Order No. PB87-206108, and 54FR 52251 (December 20, 1989).

83 See discussions in US EPA, "BackgroundInformation Document for the Development ofRegulations for PIC Emissions from HazardousWaste Incinerators", October 1989. (Draft FinalReport), and Engineering Sciences, "BackgroundInformation Document for the Development ofRegulations to Control the Burning of HazardousWaste in Boilers and Industrial Furnaces, VolumeIII: Risk Assessment", February'1987. (Availablefrom the National Technical Information Service,Springfield. VA, Order No. PB 87 173845.)

temperatures in hazardous wastecombustion devices as well.

PART FOUR; PERMIT PROCEDURES ANDOTHER ISSUES

I. Impact on Existing Permits

Upon promulgation of today'sproposed rule, EPA will use its authorityto reopen existing permits to includeconditions necessary to comply withthese rules. This authority is found in 40CFR 270.41(a)(3) (see 52 FR 45799(December 1, 1987)), which allows EPAto initiate modifications to a permitwithout first receiving a request from thepermittee, in cases where newregulatory standards affect the basis ofthe permit.

In addition, permit writers will beexpected to continue to implement theappropriate controls on metals, HCI, andPIC emissions proposed here on apermit-by-permit basis without waitingfor promulgation of the final rule.Because many incinerators arescheduled to be permitted in the interimand due consideration of the risk posedby metals, HCI, and PIC emissions isneeded, this case-specificimplementation will ensure adequateprotection of public health. Permitwriters can implement appropriatecontrols under the omnibus authority ofsection 3005(c)(3) of HSWA and codifiedat § 270.32(b)(2). The omnibus provisiongives the permit writer the authority toestablish permit conditions as necessaryto protect human health and theenvironment. Like the proposed rule, theAgency's current guidance documents 84

Screening Limits for metals and HCI todemonstrate that emissions areacceptable, and if the Screening Limitsare exceeded, the applicant mustdemonstrate by site-specific dispersionmodeling that emissions will not resultin exceedances of acceptable ambientlevels. The PIC guidance document alsouses the two-tiered approach proposedin today's rule to limit CO and HCconcentrations. in stack gas.

II. Waste Analysis Plans and Trial BurnProcedures

The proposed metals controls willimpose added sampling and analysesrequirements at hazardous wasteincinerators burning wastes with levelsof metals that are likely to exceedemission limits, or related metal feedrates. EPA anticipates that existingwaste analysis plans, and trial burn

84 U.s. EPA, "Guidance on Metals and HydrogenChloride Controls for Hazardous WasteIncinerators," August 1989, and U.S. EPA."Guidance on PIC Controls for Hazardous WasteIncinerators," April 1989.

procedures at many, if not all, facilitieswill need to be reviewed and modified.

A. Waste Analysis Plans

Existing rules require the owner oroperator to conduct sufficient wasteanalysis to verify that waste feed to theincinerator is within the physical andchemical composition limits specified inhis permit (see § 264.341(b)).

Compliance with the metals controlswill probably require many operators toconduct additional analyses forAppendix VIII metals or to require thegenerator of the waste to provideinformation on the metal content ofwaste sent to the incinerator. Therewould be a requirement to keep recordsof such analyses. To show compliancewith the feed rate limit requirements,there would be a need for sampling ofblended wastes as fed to the incinerator,or for recordkeeping to show, bycalculation, the amount of metals inwastes that are blended. Comments onthe practicality of compliance withmetals sampling, analysis, andrecordkeeping are requested.8 5

EPA's best determination ofappropriate metals sampling andanalyses procedures are given inAppendix A. Matrix effects have beenshown to be important in the analysis ofmetals in oils and solids. Accordingly,recommended sample preparationmethods are given in Appendix A.Standardized protocols are not yetwidely available, but EPA's experienceindicates that published EPA Methodsfor individual metals and particulatematter work well. It is likely that anyprotocol will require metal analysis ofwaste feeds, residual streams (bothsolid and liquid), and flue gas. Operatorsmay wish to sample flue gas both beforeand after air pollution control devices.EPA's present rules allow the use ofequivalent methods of analyses upon ashowing of substantial scientificvalidity.

B. Trial Burn Procedures

All samples must be analyzedaccording to the appropriate methodsspecified in "Test Methods forEvaluating Solid Wastes: Physical/Chemical Methods," EPA publicationSW-e46, as incorporated by reference in40 CFR 260.11. Sampling for metals mustbe done using the Multiple Metals trainsummarized in Appendix A. TheMultiple Metals train and the methodsto monitor CO, HCL, and THC are

6we note that we have requested commentearlier in the text on approaches other than wasteanalysis combined with feed rate limits toimplement the controls on metals emissions. Seealso 54 FR 43760 c.3.

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Federal Register / VoL 55, No. 32 / Friday, April 27, 1990 / Proposed Rules

discussed In more detail In "ProposedMethods for Stack EmissionsMeasurement of Carbon Monoxide,Oxygen, Total Hydrocarbons, HCI, andMetals at Hazardous WasteIncinerators," as referenced above.

The analysis procedure consists oftwo steps: Preparation (called digestion)and the analysis itself. The digestionprocess is dependent on both theanalysis procedure and the wastematrix. Appendix A lists the digestionmethods and the proper analysistechnique and waste matrix of each one.The analysis procedures are metalspecific. For some metals, up to threemethods are applicable depending onthe precision of the detection limitdesired. See Appendix A for the properanalysis methods to be used for eachmetal. In some cases, the analysismethod includes its own digestion stepand the listed digestion methods are notnecessary.

Analysis for matrix effects(interference) should be performed bythe Method of Standard Addition orother appropriate procedures.III. Emergency Release Stacks

EPA is clarifying today that noemergency release stack openings areallowed while hazardous waste is in theincinerator unless the applicant hasdemonstrated during the trial burn thatthe performance standards of § 264.343will be met while a dump stack is beingused. When such "dump" stacks areused. combustion gases bypass theemissions control equipment, and thiswould cause violation of the permitrequirements to operate the controlequipment. Therefore, the use ofemergency release stack openings whilehazardous wastes remain in thecombustion chamber would be aviolation of the permit and subject toenforcement action as deemedappropriate by the Agency. During theopening of a dump stack, emissions ofmetals and HCl could pose unacceptablehealth risk. In addition, if temperaturesat the inlet to the dump stack are notmaintained at permit levels, HCemissions could also pose substantialhealth risk. While it is understood thatthere can be mitigating circumstanceswhich require the use of emergencyrelief stacks, these instances should beminimized. Under the Preparedness andPrevention and Contingency Planrequirements of Subparts C and D, theapplicant should address what they willdo to prevent the use of the dump stackand the release of hazardous wasteconstituents into the air, and what theywill do to minimize the hazard fromsuch releases (such as backup systems,maintaining flame, temperature and

combustion air to dombust organics).See proposed § 270.62(b)(2)(vii).

IV. POHC Selection

One of the criteria for POHC selectionfor demonstration of DRE is degree ofdifficulty to incinerate the compound.There are a number of "incinerabilityindices" that could be used, but heat ofcombustion has been considered bymany to be the best index currentlyavailable. EPA studies 86 indicate,however, that a ranking based onthermal stability under low oxygen(substoichiometric) conditions maycorrelate with field test data on DREbetter than heat of combustion. Theranking was developed using lab-scalereactors to determine the temperaturerequired to destroy 99 percent of a givenPOHC in two seconds undersubstoichiometric (% stoichiometricoxygen) conditions. Mixtures of POHCswere tested together to ensure thatadequate OH and H radicals wereavailable for compounds that undergobiomoleculcar reactions. Modelingindicates that thermal decomposition inthe flame gases is essentially complete.Thus, any unburned POHCs are mostlikely the result of small fractions of thewaste escaping flame temperatures byseveral potential failure mechanisms(e.g., poor atomization). Once in thepost-flame zone, the gas phase thermaldecomposition kinetics controls the rateof POHC destruction. This wouldexplain why the low oxygen thermalstability index (TSLoO2 ) whichsimulates post-flame conditions,appears to correlate better with fieldtest DRE data than heat of combustion,autoignition temperature, and thermalstability under excess oxygenconditions.

Although the TSLoO, has not beenfield validated, EPA believes it is apromising approach to predicting therelative stability of POHCs in thecombustion environment likely to resultin unburned POHCs (and low DRE). TheTSLoO2 index is presented in U.S. EPA,"Guidance on Setting Permit Conditionsand Reporting Trial Burn Results:Volume I1 of Hazardous WasteIncineration Guidance Series", EPA/625/6-89/019, January 1989. Thermalstability values have been determinedby actual testing for approximately 80Appendix VIII compounds. Thesethermal stability values have been usedto predict the thermal stability valuesfor the remaining Appendix VIII organiccompounds based on assumed reactions

86 Taylor. P, and Deinger. R., '"Development of aThermal Stability Based Index of Hazardous WasteIncinerabilit'". UDRI FY 88 Status Report for CR813938. November 1988.

considering structural relationships ofthe compounds.

We note that some compounds thatrank high on the heat of combustionindex rank do not rank high on theTSLoO,. For example, carbontetrachloride ranks very high on the heatof combustion index but near the middleof the TSLoO 2. Given the currentuncertainty about which index betterrepresents incinerability, we recommendthat the permit writer and applicantconsider the TSLoO2 as well as otherindices when selecting POHCs andidentifying compounds in the permit thatan incinerator is allowed to burn. Infact, the TSLoO2 index has beenavailable to permit writers for over ayear. Many permit writers have used theindex to help select POHCs for trialbums needed to support permits issuedby the RCRA-mandated deadline ofNovember 1989 for existing facilities.

The Agency is continuing to validatethe TSLoO2 and to address otherquestions (e.g., are there sampling andanalysis procedures for thosecompounds high on the TSLoO2) andhopes to be able to be more definitiveabout a preferred index when today'sproposed rule is promulgated. Wespecifically request comment on the useof the TSLoO 2 index for the purpose ofPOHC selection.

V. POHC Surrogates

A number of lab scale, pilot scale, andfield tests have investigated the use ofnontoxic tracer surrogates (one exampleis sulfur hexafluoride (SF)) for POHCsselected from appendix VIII of part 261.Sulfur hexafluoride, in particular, showspromise as a conservative tracersurrogate. It is readily availablecommercially, inexpensive, andnontoxic. Appendix VIII POHCs,especially when spiking is required toincrease concentrations in the waste forDRE testing, are often difficult to obtain,expensive, and a health hazard tooperators. Sampling and analysistechniques for SF6 are well documentedbecause it has been used for years as atracer for monitoring ambient air.Sampling techniques for appendix VIIIcompounds (i.e., VOST and MM5) arecomplicated, expensive, and even forthose with years of experience, prove toproduce substantial numbers ofmeasurements that do not meet QA/QCstandards.

Given the substantial benefits of usingSF6 as a tracer compound, the Agency isconducting additional testing andanalysis to answer remaining questions.For example, the DRE of SF has beencorrelated to the DRE of only a fewappendix VIII compounds, and

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sometimes, under conditions that maynot be representative of typicalincineration operations. In addition,standard procedures are needed forfeeding and stack sampling the tracer.The Agency hopes to be able to publisha Notice of Data Availability in theFederal Register later this year topresent the results of the testing and topropose categorically that SF6 is anacceptable surrogate for appendix VIIIPOHCs. Ideally, the proposal would bepromulgated with the rest of today'sproposal.

We note that we are proposing todayto revise § 264.342(b)(1) and § 270.62(b)(4), (bX4)(i), and (b)(4)(ii) to delete therequirement that a POHC must be listedin Appendix VIII. We are proposing thischange now to give permit writers andapplicants the option of using nontoxictracers for DRE testing where theapplicant provides sufficient data todemonstrate that the tracer is anadequate surrogate.

We specifically request informationpertaining to the use of SF6 and othernontoxic tracer compounds as POHCsurrogates.

VI. Information Requirements

Information requirements may beimposed on a case-by-case basisdepending upon the complexity of riskanalysis and dispersion analysis neededat a particular location. The addedburden will be significantly increasedover existing part B requirements onlyfor facilities in unusually complexterrain situations or whererepresentative meterological data arenot available. All facilities intending tocombust hazardous waste With amountsof metals that may exceed emissionlimits will be required to submitinformation needed for determining theterrain and urban/rural classification ofthe facility. Because the determination isbased in part on using the concept ofterrain-adjusted effective stack height,site specific parameters will be neededfor all sites. Information needs areoutlined below.

If available meterological data are notconsidered representative of the site, ascreening model that does not requirethe use of site-specific meterologicaldata cam be used. We have developed ascreening model that may beappropriate in such situations. Seeappendix V of the "Guidance on Metalsand Hydrogen Chloride Controls forHazardous Waste Incinerators." Wenote, however, that a screening modelthat does not use site-specificmeterological data is designed to bemore conservative (i.e., predict higherambient concentrations) than a"regulatory" model recommended by

EPA's "Guideline on Air Quality Models(Revised)".

Reference information neededincludes facility name, address,telephone number, and the number ofhazardous waste combustion sources onsite. Site information includes stackparameters and terrain parameters. Thestack parameters consist of physicalstack height, exhaust temperaturre,inner stack diameter, exit velocity, flowrate, latitude/longitude or UTMcoordinates. Terrain parameters consistof maximum terrain rise (in meters forthree distance ranges, 0-0.5 kin, and 0-5kin). and shortest distance to fenceline.Waste firing information neededincludes stack release identifications byincinerator, a number of incinerators,maximum waste feed rate by inputlocation (nozzle, lance, ram, etc.), andmetal feed rate for liquid wastes, solidwastes, and organometals. Additionalparameters needed are the dimensionsfor all buildings within 5 buildingheights or the maximum projectedbuilding width of the stack. For thesebuildings, the following data are needed;the distance from the stack, distancefrom the nearest fenceline, buildingheight, building length, and buildingwidth.

EPA requests comment on therecordkeepin and reporting burdenassociated with these informationrequirements.

VII. Miscellaneous Issues

EPA today proposes to amend§ 264.345(a) to clarify that theincinerator must operate in accordancewith the operating requirementsspecified in the permit whenever there ishazardous waste in the incinerator.

In addition, we propose to amend§ 270.62(b)(8) to require that all datacollected during any trial bum must besubmitted within 90 days of completionof trial burn. This requirement is toensure timely submission of trial bumdata. Section 270.62(b)(10) would berevised to require that three runs mustbe passed for each set of permitconditions. This is to clarify that theruns are not to be averaged, but must bepassed each time for all standards.Section 270.62(b)(10) does allow for oneof the three runs to be disregarded if theDirector believes there is sufficientreason. EPA's criteria for disregarding arun are discussed in U.S. EPA,"Guidance on Setting Permit Conditionsand Reporting Trial Bum Results:Volume II of Hazardous WasteIncineration Guidance Series", EPA/625/6-89/019, January 1989.

EPA today clarifies § 264.340(c) whichprovides an exemption from allrequirements other than waste analysis

and closure for ignitable, corrosive orreactive waste containing insignificantconcentrations of the hazardousconstituents listed in appendix VIII, part261. In the past, this has beeninterpreted to mean organics inappendix VIII. Now that EPA isproposing to control metals emissionsand has a method to determine risksfrom metals, metals in appendix VIIIshould also be considered whengranting this exemption. Insignificantconcentrations can be taken from thefeed rate screening levels that would beused to implement the metals controls.See appendix D of the October 26, 1989,boiler/furnace supplemental notice.Further, it is possible for a waste to beexempted for one type of appendix VIIIconstituent and not the other. Forexample, if the waste containsinsignificant concentrations of metalsbut significant concentrations oforganics, then the waste could beexempt from the requirement for metals,but not for organics (e.g., DRE, CO/HClimits).

Finally, we propose to note minorrevisions to the following sections toconform with today's proposed controls:Specific part B information requirementsfor incinerators § 270.19 (a), (c)(1)(iii),(c)(3), (c)(6)(ii). [c)(7)(i}. (c)(7}(ii).(c)(7}(iii}, (c}(9)(i), (c)(9){ii), (e), (f);

Hazardous waste incinerator permits§ 270.62 (b)(2)(i)(c), (b)(2)(i)(D),(b}(2}{i)(E), (b}(6)(i}, (b}(6}(ii}, (b}(6)(iii),(b}(O)(v}, (b)(O}(viii), (b}(O)(ix}, (c), (c)(1).

All of today's proposed amendmentswould be effective immediately uponpromulgation of the final rule. Giventhat we believe that all of thesubstantive provisions are necessary toadequately protect public health and theenvironment and will, thus, be subject toimplementation under the omnibusprovision during the permitting processbefore promulgation, applicants shouldhave ample time to comply. Forexample, permits under developmentwhen the final rule is promulgatedshould already incorporate the newcontrols under the omnibus provision.

VIII. Halogen Acid Furnaces

In the May 6, 1987, proposed rule (52FR 17018--9), EPA proposed to addhalogen acid furnaces (HAFs) to the listof industrial furnaces under § 260.10. Weare today requesting comment onrevisions we are considering to the HAFdefinition, and proposing under§ 261.2(d) to list inherently waste-likematerials that are fed to a HAF ashazardous waste.

HAFs bum halogenated secondarymaterials as an ingredient to producehalogen acid product, EPA proposed to

17891178.ql



list HAFs as industrial furnaces forreasons discussed in the May 6, 1987,proposal. To ensure that the device wasinvolved in bona fide production of acidas an integral component of amanufacturing process, the proposeddefinition required that: (1) The furnacemust be located on-site at a chemicalproduction facility; (2) the waste feedmust be halogenated; and (3) the acidproduct must have at least 6% acidcontent. Based on comments on theproposal and further consideration bythe Agency, we are considering revisingthe definition to better distinguishbetween HAFs and halogenated wasteincinerators equipped with wetscrubbers to control halogen acidemissions and to better reflect industrypractice.

To ensure that the device is anintegral component of a chemicalmanufacturing process, we haveproposed that a substantial fraction ofthe acid product be used on-site. Thus,we would add to the definition that atleast 50% of the acid product be used on-site. In addition, we would require thatany off-site waste fed to the HAF mustbe indigenous to the chemicalproduction industry. Thus, the wastemust be generated by a SIC 281(inorganic chemicals ) or SIC 286(organic chemicals) process.

To ensure that the waste is burned asa bona fide ingredient to produce ahalogen acid product, we would requirethat any waste fed to the HAF musthave an as-generated halogen content ofat least 20%.

To better reflect industry practice, wewould require that the acid product havean halogen acid content of 3% ratherthan 6%. We believe that this would stillclearly distinguish an incineratorhalogen acid scrubber water from theacid product of an HAF becauseincinerator scrubber water has an acidcontent well below 1%.. Finally, we are proposing pursuant to

§ 261.2(d)(2) to list hazardous waste fedto a HAF as inherently waste-likematerial. Materials fed to the HAFs areusually the residual still bottoms nolonger suitable for use as feedstock tomake new chemical products. Many arelisted wastes, for example thegenerically listed F024. These materialscontain dozens of appendix VIIIconstituents not ordinarily found in theraw materials that are normallyused toproduce chlorine. See the various listingbackground documents for the listedwastes from chlorinated organicproduction, as well as appendix VII ofpart 261 for these listings. Other than fortheir chlorine content, these organictoxicants do not contribute tohydrochloric acid production; they are

destroyed (assuming the HAF operatesefficiently). Thus, these toxicants (whichby volume comprise the greater part ofthese wastes) are discarded by thermalcombustion. Second, inefficientcombustion of the halogenated organiccompounds in wastes fed to a HAF canpose the same risks to human health andthe environment as combustion of thosewastes in an incinerator, boiler, or otherindustrial furnace. We thus believe thatthe hazardous materials burned in thesedevices are inherently wastelike.

We note, that to the best of EPA'sknowledge, all of these materials arepresently regulated as hazardouswastes, because the devices in whichthey are burned are either classified asincinerators or burn partially for energyrecovery. Given, however, that thewastes are used as an ingredient toproduce the acid product, the HAFwould not be subject to regulation if the*wastes were not burned partially forenergy (or materials) recovery.Halogenated wastes with a heatingvalue of less than 5,000 Btu/lb could beconsidered to be burned solely as aningredient in a HAF. Thus, we proposeto list as inherently wastelike materialany secondary material that is identifiedor exhibits a characteristc of ahazardous waste provided in subparts Cor D of part 261. See proposed§ 261.2(d)(2).PART FIVE: ADMINISTRATIVE, ECONOMICAND ENVIRONMENTAL IMPACTS

I. State AuthorityA. Applicability of Rules in AuthorizedStates. Under section 3006 of RCRA, EPAmay authorize qualified States toadminister and enforce the RCRAprogram within the State. (See 40 CFRpart 271 for the standards andrequirements for authorization.)Following authorization, EPA retainsenforcement authority under sections3008, 7003, and 3013 of RCRA, althoughauthorized States have primaryenforcement responsibility.

Prior to the Hazardous and SolidWaste Amendments of 1984 (HSWA), aState with final authorizationadministered its hazardous wasteprogram entirely in lieu of EPAadministering the Federal program inthat State. The Federal requirements nolonger applied in the authorized State,and EPA could not issue permits for anyfacilities in the State which the Statewas authorized to permit. When new,more stringent Federal requirementswere promulgated or enacted, the Statewas obliged to enact equivalentauthority within specified time frames.New Federal requirements did not take

effect in an authorized State until theState adopted the requirements as Statelaw.

In contrast, under section 3006(g) ofRCRA, 42 U.S.C. 6926(g), newrequirements and prohibitions imposedby HSWA take effect in authorizedStates at the same time that they takeeffect in nonauthorized States. EPA isdirected to carry out those requirementsand prohibitions in authorized States,including the issuance of permits, untilthe State is granted authorization to doso. While States must still adoptHSWA-related provisions as State lawto achieve or retain final authorization,the HSWA applies in authorized Statesin the interim.

Today's rule is proposed pursuant tosections 3004 and 3005 of RCRA. Thus,as a non-HSWA rule, it is'not effectivein authorized States until such time asthe State is authorizedto implementthem. However, the EPA has authorityunder section 3005(c)(3), the HSWAomnibus provision codifed at 40 CFR270.32(b)(2), to impose any permitcondition deemed necessary to protecthuman health and the environment. Thisprovision can be invoked whenever afederal RCRA permit is issued (includingfederal permits implementing HSWAprovisions that are issued concurrently .with permits issued by an authorizedState for the same unit). Thus, all federalpermits-including those incorporatingthe HSWA corrective actionrequirements-could include conditionsbased on EPA's omnibus authority. TheEPA has decided that the requirementsin today's rule relate to permitconditions deemed necessary to protecthuman health and the environment andthat such conditions are needed for allfuture permits to minimize risks fromtoxic emissions of PICs, metals, and acidgases. So, until such time as theauthorized States are able to imposethese now requirements in permits theyissue, EPA can impose them under thedirect authority of § 270.32(b)(2) inauthorized and unauthorized States,effective the date of promulgation of thisrule, whenever a-Federal RCRA permit(or Federal portion of a RCRA permit) isissued with respect to the facility. Priorto the effective date of these regulations.permit Writers may impose these sameconditions (or others) at their discretion,in Federal permits pursuant to the sameauthority. (See part Four, I. Impact onExisting Permits. The metals/HCl andPIC guidance documents can be used toimplement these requirements prior topromulgation of the rule).

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B. Effect on State AuthorizationsAs noted above, today's rule proposes

standards that would be effective viaomnibus authority in all Statesregardless of their authorization status.Nonetheless, the authorized States mustalso revise their program and adoptequivalent requirements under theirState law by the deadlines set forth in§ 270.21(e).

Section 271.21(e)(2) requires thatStates that have final authorization mustmodify their programs to reflect Federalprogram changes and must subsequentlysubmit the modifications to EPA forapproval. The deadline by which theState must modify its program to adoptthis proposed regulation will bedetermined by the date of promulgation

"of the final rule in accordance with§ 271.21(e). These deadlines can beextended in certain cases (40 CFR271.21(e)(3)). Once EPA approves themodifications, the State requirementsbecome subtitle Cv RCRA requirements.

States with authorized RCRAprograms may already haverequirements similar to those in today's-rule. These State regulations have notbeen assessed against the Federalregulations being proposed today todetermine whether they meet the testsfor authorization. Thus, a State is notauthorized to carry out theserequirements in lieu of EPA until theState program modification is submittedto EPA and approved. Of course, Stateswith existing standards may continue toadminister and enforce their standardsas a matter of State law. In fact, EPAencourages States with similarstandards or with their own omnibusauthority to impose these newrequirements as soon as possible.

States that submit their officialapplication for final authorization lessthan 12 months after the effective dateof these standards are not required toinclude standards equivalent to thesestandards in their application. Howeverthe State must modify its program by thedeadlines set forth in § 271.21(e). Statesthat submit official applications for finalauthorization 12 months or more afterthe effective date of those standardsmust include standards equivalent tothese standards in their application.Section 271.3 sets forth the requirementsa State must meet when submitting itsfinal authorization application.

I. Regulatory Impact Analysis

A. Purpose and Scope

EPA has determined that today'sproposed rule is not a major rule asdefined by Executive Order 12291. Thissection of the preamble discusses theresults of the cost impacts and risk

analyses of the proposed rule. EPA hasalso assessed small business impactsresulting from the proposed rule, asrequired under the Regulatory FlexibilityAct.

The costing analysis and riskassessment were constrained by dataavailability. The major limitations thatshould be considered when reviewingthe results are summarized below:

- The main focus of the RegulatoryImpact Analysis (RIA) was the analysisof the proposed 1X10 - 5

87 risk standard;however, a less detailed analysis of analternative (1X 10- de minimis riskstandard was also performed.

e Because of data limitations, the RIAevaluated only seven of the ten toxicmetals covered by today's proposedrule. Waste characterization data byRCRA code could not be located forthallium, antimony, and silver.

a At this time, EPA was unable tocomplete a detailed analysis of thechlorine content in differnt wastescurrently being incinerated. As asurrogate, EPA calculated an averagechlorine concentration in all hazardouswaste combusted using available testburn data.

* The llIA estimated only theincremental costs of the proposed COmonitoring that includes a continuousoxygen monitor and a data-logger forcontinuous oxygen corrections. Becauseof time and resource constraints, theanalysis did not consider the proposedalternative requirement (a CO monitorand a timer) which could be less costly.

* There was insufficient informationto quantify the potential human risksposed by PICs or total residualhydrocarbons at the present time.

* EPA did not perform an extensiveeconomic impact analysis. A prelimaryestimate ofeconomic impact was madeby completing a financial ratio test.

B. Affected PopulationCurrently available information in

EPA's Hazardous Waste DataManagement System (HWDMS) lists 227active hazardous waste incinerators(approximately 207 noncommercial and20 commercial) that will be subject tothe proposed requirements."8 Theseincinerators are widely dispersedthroughout the country (41 states plusPuerto Rico). Texas has the mostincinerators with 27 facilities (12percent), followed by Louisiana andOhio, each with 17 facilities (7 percent),

87 In selecting a risk threshold of 1O- 'for theserules. EPA considered risk thresholds in the range of10-

4 to 10 - . As discussed in section I.D. of partthree of the text, the Agency requests comment onalternative risk thresholds.

88 USEPA, HWDMS, Version 6.5, October 9,1987.

and California with 15 facilities (7percent). Thirty-eight states, each withbetween 1 and 12 incinerators, togetheraccount for 67 percent of the total.

Information on the characteristics ofeach incinerator (e.g., type of combustor,existing air pollution controls, anddescription of the type and quantity ofwaste combusted) was not readilyavailable. As a result, EPA relied ondata reported in the 1982 HazardousWaste Incinerator Mail Survey, whichcontains information (from 1981) on asample of 110 nonconfidential facilitiescomprising 152 units.89 The surveyresponses for these incinerators wereexamined for completeness regardingnecessary information and for deletionof facilities no longer active. Based onthis evaluation, a subset of thesefacilities-82 facilities (74noncommercial and 8 commercial), 112units--were selected as the sampledatabase for this analysis. The results ofthe sample were then extrapolated tothe total population of 227 hazardouswaste incinerator sites (310 estimatedunits). Implicit in the extrapolation is theassumption that the distribution ofincinerators and waste characteristics(e.g., number of units, type of combustor,wastes combusted, current controls, andstack data) is the same in the sample asit is in the population.

According to the Mail Survey data forthe 112 incinerator units evaluated, mosthazardous waste incinerators are liquidinjectors (54 percent). The remainingincinerator units are classified asmultiple chamber (12 percent), rotarykiln (8 percent), controlled air (8percent), and other (19 percent).

The Mail Survey data for the samplefacilities/units show that approximately42 percent of the hazardous wasteincinerators did not have air pollutioncontrol devices (APCDs) in place in1981. Most of the remaining incineratorunits (48 percent) had treatment trainsthat included a wet scrubber. Very few(approximately 29 percent) had othertechnologies, such as electrostaticprecipitators (ESPs), venturi scrubbers,and fabric filters, used to captureparticulates.

The facilities evaluated fall into 40different industrial categories, asdefined by the foui-digit StandardIndustrial Classification (SIC) codes (seetable 4). Most industrial SIC codesaccount for less than 2 percent of thefacilities. The SICs with the largestpercentage fractions of hazardous wasteincinerators are:

89 The Mail Survey also contains data for anadditional 15 confidential facilities (18 units), butthis information was not used in this analysis.

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* 2821 Plastics Material (10 percent).* 2869 Industrial Organic Chemicals

(10 percent).* 4953 Refuse (Waste Management)

Systems (8 percent).e 7391 Research and Development

Laboratories (7 percent).* 2865 Cyclic Crudes and

Intermediates (5 percent).e 2879 Agricultural Chemicals (5

percent).An estimated 1.0 million kkg of

hazardous waste were combusted inincinerators in 1986.e 0 As shown inTable 4, the. majority of the wasteburned by hazardous waste incineratorsis concentrated in six industrial SICcodes:

* 2819 Industrial Inorganic Chemicals(46 percent).

* 2879 Agricultural Chemicals (13percent).

* 2833 Medicinal Products (7 percent).* 2865 Cyclic Crudes and

Intermediates (6 percent).* 2869 Industrial Organic Chemicals

(6 percent).

• 2834 Pharmaceutical Preparations (5 grouped into two major categories: costspercent). to demonstrate compliance with the

The hazardous waste analyzed is proposed standards and costs to reducecharacterized by almost 60 different emissions if a facility cannot showRCRA codes. Two waste codes account compliance with the pollutant-specificfor the majority (71 percent) of limits. The methodology and engineeringhazardous waste combusted: D001 unit costs used by EPA to estimate the(ignitable wastes) and X182 (a mixture incremental compliance costsof U008-acrylic acid, U112-ethyl attributable to each of the threeacetate, U113-ethyl acrylate, and standards are discussed below, followedP003-acrolein). This analysis by a presentation of results. The costingdetermined that approximately 44 analysis was performed for the subset ofpercent of the hazardous waste 82 facilities selected from the Mailcombusted contains the metals of Survey; results were extrapolated to theconcern for today's rule and roughly 37 population of 227 facilities.percent of the hazardous waste contains As a sensitivity analysis, EPA alsochlorine, completed a preliminary assessment of

C Costing Analysis the incremental compliance costs

Today's rule proposes limits for associated with an alternative deemissions of toxic metals, hydrogen minimis cancer risk level of I xio- .chloride (HCI), and carbon monoxide This section also presents the unit cost(CO) as a means of controlling total estimates used in the sensitivityunburned hydrocarbons (THCs) from analysis and the total predictedhazardous waste incinerators. The compliance costs under this alternativeincremental costs of compliance can be scenario.

TABLE 4.-DISTRIBUTION OF HAZARDOUS WASTE INCINERATORS AND HAZARDOUS WASTE COMBUSTED BY SIC

Facilities Quantity of hazardous waste

SIC Description combustedNo. Percentage (KKG/Year) Percentage

2231 ........2282.2421.2491.2511.2661 .......2 8 13 . -2819.**'*...2821.-....2822........2824.-..2833........2834 . -...2844.2851.2861....2865........2869.-..2873........2879......2891.2892.2899.2911.3079.3229.3339.3412.3433.3466.3483.3531.3672 ........

4953 ........

Broad woven fabric m ills ............................................. ...........................................................Yam texturizing m ills ................................................................................................................Sawm ills and planing m ills .......................................................................................................W ood preserving ........................................................................ .........................................W ood household furniture .........................................................................................................Building paper/board m ills ................................................................ ..........Industrial gases.............................. ..................... ..............Industrial Inorganic ch ................................................................................ . . . .Plastic m aterial ........................... ......................................................................................Synthetic rubber ..........................................................................................................................Synthetic org be r ...................................................................................................................M edicinal products ..................................................................................................................M ed ia lc t pr epdrcts on ..... ............................................................................................... ............Pharm aceut. preparations ........................................................ .........................................Perfumn es/cosm etics ................................................................................................................Paints/allied products ........................................................................................... .......Gum and wood chemicals............................Cyclic crudes, org. pigments ....................................................................................................Ind. organic chem icals ........................................ : ......................................................................Nitrogenous fertilizers ................................................................................................................Pesticides/agric. chem ..............................................................................................................Adhesives/sealants ....................................................................................................................Explosives..... . ............................................................................................................................Chem ical preparations ...................................................................................................... : ......Petroleum refining ......................................................................................................................Misc. plastics .......................Pressed/blown glass ..........Prim. smelting nonferrous...Metal shipping barrels, etc.Heating equipment ..............Crowns and closures ..........

.1 Ammunition ................................................................................................................................Construc. machinery eCathode ray TV tubesA;r--ft

tquip ......................................................................................................

Refuse systems

114

3105388268

7,177493,167

28,847408190

69,37547,392

1,1774,4912,001

69,22768,40926,956

141,640242

1,45960

2,897242

4,493651

209

79788

5,0413,877

9934,596

50 EPA developed this estimate based on the MailSurvey data for the subset of facilities analyzed.Because capacity conditions have changeddramatically since 1981, the waste figures werescaled up to 1986 (the baseline for this analysis)using different factors for commercial (1.27) and

noncommercial (1.13] incinerators. The commercialscaling factor was based on an annual survey ofcommercial capacity conducted by EPA (USEPA,Office of Policy Analysis, "Survey of Selected Firmsin the Commercial Hazardous Waste ManagementIndustry"). Because a similar type of annual survey

could not be located for noncommercial facilities,the ratio of industrial production in 1986 versus 1981was used as a scaling factor. (Source: Board ofGovernors of the Federal Reserve System, totalindustrial index).

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.. ....................................................................................................

................................................................. I ........... I ...................... 11

................................. I ....................................................................I ............................. I ................................. I ....................................

......................................................................................................

......................................................................................................

I ..........................-J / ,J 1



TABLE 4.-DISTRIBUTION OF HAZARDOUS WASTE INCINERATORS AND HAZARDOUS WASTE COMBUSTED BY SIC-Continued

Facilities Quantity of hazardous wasteSIC Dscritioncombusted

SIC No. Percentage (KKG/Year) Percentage

7391 . Research/develop. labs ............................................................................................................. 17 7 1,333 08062 ........ Gen. med./surg. hospitals ........................................................................................................ 3 1 42 0

8221 ......... Colleges, universities ....................................................................................................... 6 2 120 09661 ......... Space research & technology .................................. 3 1 364 09999 . Nonclassiflable establish ...................................... ; ................................................................. 8 4 19,716 2

Total ....................................................................................................................................................... 227 100 1,035,362 100

'Numbers may not total because of rounding.

1. Costing Methodology and Unit Costsof Control

Toxic Metals Limits. As discussed,EPA is proposing a site-specific riskanalysis to ensure that emissions ofmetals do not pose unacceptableincreased risks to human health. EPA isalso proposing to allow permit writersand applicants to demonstratecompliance with the proposed risk-based standards using a conservativescreening analysis for feed rates andemissions. In conducting this costinganalysis, EPA assumed that each facilitywould attempt to show compliance in asequential fashion, as shown in Figure 1.

EPA assumed that all hazardouswaste incinerator operators would firstattempt to demonstrate compliance withthe proposed standards using the FeedRate Screening Limits. Prior to the FeedRate Screening analysis, EPA assumedthat all incinerator operators wouldincur costs to analyze the toxic metalconstituents as part of the WasteAnalysis Plan for the permit. In addition,

the Feed Rate Screen would requireincremental analysis of metals in thewaste feed as part of a trial burn. Forboth the waste characterization and thefeed analysis, the facilities will not incuradditional costs for sampling, which isalready conducted under existingregulations.

EPA assumed that all facilitiespassing the Feed Rate Screen would beawarded a permit and would not incuradditional permitting expenditures. Thefailing facilities would then attempt todemonstrate compliance using theEmissions Screening test. The EmissionsScreen would require sampling andanalysis of metals in the stack exhaustgas. e

In the event that a facility would failto satisfy the requirements of theEmissions Screen, the facility wouldconduct a Site-Specific RiskAssessment. If the risk assessmentpredicted that the facility would pose anaggregate lifetime cancer risk to themaximum exposed individual (MEI) in

excess of Ix 10 - 5 91 (summed across allcarcinogens emitted by the facility) oran increased likelihood of adverse(noncancer) health effects, the costinganalysis assumed that the incrementalemission reductions would be achievedusing APCDs.9 2 This latter assumptionmay result in an overestimate ofcompliance costs because incineratoroperators in some situations may beable to modify their combustionpractices (e.g., blending) at little or noincremental cost to meet the standards.BILLING CODE 6560-M

91 In selecting a risk threshold of 10 - 1 for these

rules, EPA considered risk thresholds In the range of10T to 10-6. As discussed in Section I.D. of PartThree of the text, the Agency requests comment onalternative risk thresholds.

"2 In this analysis, EPA assumed that acumulative lifetime cancer risk of 9.5 X10 - orgreater was equivalent to 1X10

- 5 through roundingand other uncertainties. Similarly, a ratio of 0.95 orgreater calculated as part of screening analyses orthe analysis of noncancer risks (i.e., the ratio of thepredicted ambient concentration divided by theRAC) was assumed equivalent to 1.0.

17895



24

Figeure *7

Overview of Costing Approach: Proposed Metals Limits

Comollance Demonstration Strateov

PreliminaryWaste

Characeization

All facilities conduct the prehminary wastecharacterization and the feed rate screen.

,O- Per- Awarded

PassFeed

Rate ScreenFail

PursueEmissions Screen

Oorm Permit Awarded

Emission Pass

ScreenII I Fail

PursueSite-Specfic

Risk Assessment

,4mw m Permit Awarded

S~te-Soecific Pass PRisk

AssessmertFail

InstallAPCDs

Incremental UnIt Costs

- Waste Stream Analysis (permit application): $3.810(one comosite sample of six waste streams) [a]

- Waste Feed Analysis (trial burn)- $6,008 per-HW incinerator unit [a)

- Emissions sampling and an'alysis: $25,200 perHW incinerat.enmit

* Risk Assessment: $7,500 per incinerator tacility(non-complex terrain): and S12.500 per incinerator facility(complex terran).

PLUS

Collection of S te-Specilic Meteorological Data:

$50,000 for 30% of facilities in non-complexterrain, and 70% of facilities in complex terrain

* Capital Costs: $30.000 to $660.000 per HW incineratorunitAPCDs iumE Z IJ

* Annual Operating Costs $5.000 to $180,000 perHW incineraor unct

'a] Samples are already o~tected under existing ,egulat,ons- therefore, there is no incremental cost associated with sampling

BILLING CODE 6560-50-C

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Figure I has also summarized the unitcosts associated with the metals costinganalysis. As shown, the estimatedincremental unit cost of completing thepreliminary waste characterizationanalysis as part of the permit for sixblended waste streams is $3,810. 9 3 94The additional analysis costs for theFeed Rate Screen are approximately$6,000 per hazardous waste incineratorunit; the incremental sampling andanalysis costs for the Emissions Screenare $25,200 per hazardous wasteincinerator unit.9 5 The risk assessmentcosts range from $7,500 for a facility innoncomplex terrain to $12,500 for afacility in complex terrain. 6 In addition,EPA assumed that 30 percent of thehazardous waste incinerators innoncomplex terrain and 70 percent ofthe hazardous waste incinerators incomplex terrain would need to gathersite-specific meteorological data at acost of $50,000. 9 ' EPA requests commenton the reasonableness of the riskassessment cost estimates.

Because the collection of site-specificdata could take as long as one year, EPArecommends that the nearest STAR databe used until the site-specific data canbe gathered. At that time, the permitcould be reported, and the site-specificdata used.

For each hazardous waste incineratorthat was esimated to pose an aggregatelifetime cancer risk to the MEI in excessof I x 10 "s and/or an increasedlikelihood of noncancer effects, a bestengineering estimate was developed fora treatment train and the associatedcosts needed to meet the estimated riskreduction level. The APCD capital costsranged from $30,000 to $660,000 perincinerator unit ($40,000 to $660,000 perincinerator facility), depending on thefacility type, size, existing equipment,

93 In assigning the costs for the wastecharacterization, it was assumed that ten wastestreams are blended to one. This decision rule islimited because the 10-to-1 blending assumption willnot necessarily be representative for all

'incinerators. After blending has been assumed, thewaste characterization unit costs were thenallocated as follows: 0 to a blended streams (unitcosts remain the same); 7 to 12 blended streams(unit costs are multiplied by two); 13 to 18 blendedstreams (unit costs are multiplied by three).Information on the number of waste streamscombusted at each HW incinerator was found in theMall Survey.

94 Memorandum to Frank Smith, USEPA, fromBruce Boomer. MRI, "Sampling and Analysis CostImpact of Draft Proposed Incineration Regulationsfor Metals; MRI Project No. 9029-L-Z," July 31,1987.

9 Ibid.96 Versar Inc. "Air Dispersion Modeling as

Applied to Hazardous Waste IncineratorEvaluations: Draft Report." May 13,1987.

and the amount of risk reductionrequired; annual operating costs rangedfrom $5,000 to $180,000 per incineratorunit ($10,000 to $180,000 per incineratorfacility).9

EPA assigned the costs for thepreliminary waste characterization andcompletion of the Feed Rate Screen toall hazardous waste incineratorscombusting wastes containing metals.The allocation of subsequent costsdepended on the success with whicheach incinerator passed or failed each ofthe screens and the risk. assessment. Thecosts of gathering additionalmeteorological data were randomlyassigned among those facilitiesperforming a risk assessment.

The decision rules discussed in partThree of today's proposed rule wereused to predict which facilities wouldfail the Feed Rate, Emissions, Site-Specific Risk Assessment tests forcarcinogenic and noncarcinogenicmetals. The allowable screening limitswere selected for each facility as afunction of terrain (complex andnoncomplex), terrain adjusted effectivestack height, and land usage (ruralversus urban). EPA identified the terrainfor each incinerator analyzed. Effectivestack height was calculated usinginformation from the Mail Survey.Information on land usage was notreadily available; therefore, the moreconservative screening limits were used,-as directed by today's proposed rule.

To complete the screening analysesand the risk assessment for the selectedtoxic metals, facility-specificinformation in the following parameterswas needed: metal constituentconcentrations in the waste; quantity ofeach metal emitted; a point estimate ofthe maximum ambient air concentrationoutside of the fenceline of theincinerator, and health risk factors(either unit cancer risk numbers oracceptable Reference Air Concentrationlevels (RACs) for noncancer effects).

'The analytical approaches used togather these data are discussed later inthe Risk Assessment section.

HC Limits. Identical to the proposedapproach for regulating metals, EPA isproposing a site-specific risk analysis toensure that HCl emissions do not poseunacceptable risks. Again, EPA isproposing conservative Feed Rate and

97 Ibid. Estimates of the percentage of facilitiesrequiring additional meteorological data estimatedby Versar Inc.

9s Memorandum to Temple. Barker, & Sloane, Inc.from Doucet & Mainka. P.C., "Hazardous WasteIncenerator Mini-RIA: APCD Cost Increments forOne Percent Chrome VI Scenario," September 28,1987.

Emissions Screening Limits for HCI tosimplify the permitting process. TheseHCl limits differ from those establishedfor metals only in that they providestandards relating to both short-termand long-term human health effects.

The costing analysis assumed, as itdid for metals, that all hazardousincinerator facilities would first attemptto demonstrate compliance with theproposed HC1 standard by performingthe Feed Rate Screen; all facilitiesfailing the first screen would then opt forthe Emissions Screen and any facilitiesfailing the second screen wouldundertake the Site-Specific RiskAssessment (see Figure 2). If the riskassessment predicted risks to humanhealth above the acceptable levels, thecosting analysis assumed that APCDswould be installed to reduce HClemissions. For some facilities this maybe a conservative (high cost) optionbecause there may exist lower costoptions (e.g., pretreatment and wasteblending) that the Agency was not ableto consider within the scope of thisanalysis.

EPA believes that there would be noincremental costs attributable to thepreliminary waste characterization, theFeed Rate Screen or the EmissionsScreen for HCI, because the samplingand analysis of chlorine required foreach of these tests is already performedunder the permitting conditions ofexisting subpart 0 of the Subtitle Cregulations for hazardous wasteincinerators. The incremental costs forperforming a Site-Specific RiskAssessment for HCl are equivalent inmagnitude to costs for a metals riskassessment; however, facilitiesconducting a metals risk assessmentwere not expected to incur additionalcost.

For each incinerator that failed tomeet the baseline HCI emissionstandards, considering both short-termand long-term effects, the cost analysisdeveloped a best engineering estimate ofthe treatment train and the associatedcosts needed to meet the estimated riskreduction." A detailed facility-specificanalysis was not performed. The APCDcapital costs for HCI ranged from$17,000 to $430,000 per incinerator unit;depending on the type of combustor,size, existing control equipment, and theamount of risk reduction required;annual operating costs ranged from$1,00Q to $154,000 per incinerator unit(see Figure 2).BILLNG CODE 6560-50-u

99 Ibid.

17897


Federal Register / Vol. 55, No. 82 / Friday. April 27. 190 I Prnnnosd Ries

23

Figure

Overview of Costing Approach: Proposed HCI Limits

Compllance Demonstration Strateav Incremental Unit Costs

Preliminary IWaste Characterization * Waste Stream Analysis (permit application):

no incremental costs (a)

All facilities conduct the preliminary wastecharacterization and the feed rate screen.

Permit Awarded~rnrrnrsrnn~, PassFeed

Rate ScreenFailFiu#4.

Pursue

EmissionsQrrfo

,4"ii" Permit Awarded

I PassEmissionScreen

Fail' S % Pursue

Site-SpecificRisk Assessment

Permit Awarded

[DeciiTI~ Pass

AessmentJ Fail InstallSAPC~s

* Waste Feed Analysis (trial burn):no incremental costs [a]

* Emissions sampling and analysis:no incremental costs (a]

• Risk Assessment $7,500 per incinerator facility(non-complex terrain); and $12,500 per incineratorfacility (complex terrain). [b]

PLUS

• Collection of Site-Specific Meteorological Data:$50.000 for 30% of facilities in non-complexterrain, and 70% of facilities in complex terrain. (c)

• Capital Costs: $17,000 to $430.000 per HW incineratorunit

* Annual Operating Costs: $1,000 to $154,000per HW incinerator unit

[a] Sampling and analysts of chlorine is already conducted under the permitting conditions of existing Subpart 0of the Subtitle C regulations for HW incinerators.

[b] No additional risk assessment costs were assigned to a faclility in the costing analysis if i0 was already conducting arisk assessment for metals.

[c) No additional data gathering costs were assigned to a facility if i was already performing this work for the metalsnsk assessment.

BILLING CODE 6560-60-C

17898

SAPCDsu



. The decision rules discussed in partThree of today's rule were used topredict which facilities would fail theFeed Rate, Emission, and Site-SpecificRisk Assessment tests. The RiskAssessment section below providesmore detail on the information neededto complete these tests, specifically: thequantity of chlorine emitted; a pointestimate of the maximum short- andlong-term ambient concentration outsidethe fenceline of the incinerator, andhealth risk factors (short-term and long-term RACs).

CO Limits. EPA believes thathazardous waste incinerators shouldoperate at a high combustion efficiencyto ensure that HCs do not pose anunacceptable risk to human health.Because CO is one of the best availableindicators of combuotion efficiency, EPAis proposing limits on CO emissions. Inparticular, EPA is proposing a CO limitof 100 ppmv. If a facility cannot meet theproposed CO limit, higher limits will beacceptable provided that HC emissionsare not associated with unacceptablehuman health risks or do not exceed agood operating practice-based limit.EPA is proposing a tiered approach fordetermining how HC are regulated. This

approach is similar to that beingproposed for metals and HCI.Accordingly, the costing methodologyfor PICS also resembles the analysiscompleted for metals and HCl (seeFigure 3).

Tier I is a 100 ppmv CO limit. If afacility can demonstrate compliancewith this standard, this will be thepermit limit. There is no incrementalcost associated with this demonstrationbecause emissions information isalready generated as part of the trialbum.

If a higher CO limit is sought as apermitting condition, the facility mustdemonstrate that HC levels areacceptable under Tier I. Although theAgency is proposing a health-basedapproach to limit HC, it is requestingcomment on limiting HC to atechnology-based level of 20 ppmv. Asdiscussed previously in today's notice,the Agency now prefers the technology-based approach. Nonetheless, we haveprojected implementation costs for thehealth-based alternative because thecosts would be higher. Under the health-based approach, the facility would berequired to demonstrate that HCemissions do not pose a cancer risk

greater than 1X 10 -5 100. The facilitycan compare HIC emissions withScreening Limits that the Agency hasestablished or it can conduct sitespecific dispersion modeling. Theincremental cost of performing the TierII analysis is the sampling and analysisrequired to determine emissions ofTHCs. The Agency has estimated atypical incremental cost for this test at$6,500 per incinerator unit.' 0 1

If, under the risk-based alternative toassessing HC emissions, a facility failsTier II using the decision rules discussedin part three of today's proposed rule, aSite-Specific Risk Assessment would beperformed. The cost of the riskassessment is the same as that formetals and HC1. However, noincremental cost was assigned to afacility in this analysis if it was alreadyincurring risk assessment costs foreither chlorine or metals.SILLNG CODE 6500-6"

o00 In selecting a risk threshold of 10-5 for theserules. EPA considered risk thresholds in the range of10-4 to 10- . As discussed in Section I.D. of partthree of the text, the Agency requests comment onalternative risk thresholds. "

101 USEPA, Office of Solid Waste, internalanalysis.

I il l I I I I

17899



Figure .3

Overview of Costing- Approach: Proposed CO Limits

Comoliance Demonstration Strateav Incremental Unit Costs

COilitorinj

All facilities conductCO monitoring and Tier I

JuPermit Awarded

w ,PassTier I

Fail11 . Pursue Tier 11

Permit Awarded

Ti3er 11 PursueFai Shte-SpecificWas Risk Assessment

1,in 1 Permit AwardedSite-Soecific Pass

Risk

IAssessmentIFail ModifyIlk.u. Combustion

Practices

Modify

CombustionSystem/Practices

" Capital Costs: $40,000 per HW incinerator unit

" Annual Operating Costs: $1,200 per HW incinerator unit

" Combusting of Auxiliary Fuel during Upsets: $100 permillion BTU of incinerator capacity

- Emissions Testing: No Incremental costs (a]

* Sampling and Analysis of THC Emissions: $6.500 perHW incinerator unit.

* Risk Assessment . $7,500 per incinerator facility (noncomplexterrain); and $12,500 per incinerator facility(complex terrain). [b)

PLUS• Collection of Site-Specific Meteorological Data

$50,000 for 30% of facilities in non-complexterrain, and 70% of facilities in complex terrain. [c]

- Incremental costs were not estimated. [d]

[a) Emissions testing for CO is already performed under the permitting conditions of existing Subpart 0 ofthe Subtrtle C regulations for HW incinerators.

[b] No additional risk assessment costs were assigned to a facility in the osting analysis if it was already conducting arisk assessment for metals and/or chlorine.

(c] No additional data gathering costs were assigned to a facility if it was already performing this work for the metalsand/or chlorine risk assessment.

[d] Incremental costs were not estimated because (1) there was insufficient information on the technical response, and(2) a small number of facilities (approximately five) were expected to incur costs.

BILLNG CODE 6560-G0-C

17900



For those facilities with HCconcentrations higher than allowed,EPA assumed that the incineratoroperator would modify the combustionsystem and/or practices to reduce CO(and HC) levels. EPA did not developestimates of the costs associated withcombustion modification because (1)there was insufficient availableinformation to estimate the appropriatetechnical response, (2) very fewfacilities were expected to incur costs(approximately five facilities), and thus,(3) the incremental compliance costswere not anticipated to be significant ateither the national or individual industrysector level.

To demonstrate compliance with thefinal permitted CO levels, this analysisassigned additional monitoring costs toeach incinerator. The CO monitoringprogram included a continuous oxygenmonitor and a data-logger forcontinuous oxygen correction. Thecapital costs were estimated atapproximately $40,000 per incineratorunit; annual operating costs wereestimated at roughly $1,200 per

incinerator unit.10 2 Because of time andresource constraints, this analysis didnot include the proposed alternative COformat described in today's proposedrule, although it is expected to provide alower-cost alternative.

The costing analysis also included theincremental expenses associated withcombustion of auxiliary fuel duringperiods of upset, as required in today'sproposed rule. The annual incrementalcost of the auxiliary fuel was estimatedat roughly $100 per 106 Btu of incineratorcapacity based on 50 upsets of one-hourduration per year.1 ° 8 This cost wasassigned to all incinerator units.

Because of data limitations, thisanalysis was unable to estimateemissions of CO and THCs for the

109 Doucet & Mainka analysis of "Guideline forContinuing Monitoring of Carbon Monoxide atHazardous Waste Incinerators," Jam, ary 13, 1987prepared by Pacific Environmental Services forUSEPA.

3 Memorandum to Temple, Barker & Sloane,Inc. from Doucet & Mainka, P.C., "Hazardous WasteIncinerator Mini-RIA Supplemental Information toUnit Costing Methodology (draft)," August 18,1987.

facilitJes analyzed in the Mail Survey.As a result, it was not possible toquantify the number of facilities thatwould pass Tier I, Tier II, and the Site-Specific Risk Assessment using themethods employed in the metals andHCl analysis. Alternatively, a decisiontree analysis was used to obtainapproximate estimates regarding thenumbers of facilities that might besubject to incremental impacts and costsassociated with the proposed COstandards.

Figure 4 illustrates the decision tree.Based on available engineering opinion,the Agency believes that the onlyfacilities that would be unable to meetthe proposed CO limits would be fluidbed incinerators and incineratorsfeeding 10 percent or more of theirwaste in large containers. The Agencyestimates that a subset of 19 facilities (8fluid bed and 13 burning containerizedwastes) would be in this category andassumed to pursue Tier II.BiWNG CODE 6O60-50-

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Federal Register / Vol. 55, No. 82 / Friday, April 27,- 1990 / Proposed Rules

For purposes of determining order-of-magnitude costs, EPA subjectivelydetermined that half of these facilities,randomly assigned, would pass Tier II(i.e., would be permitted without furthercosts). The remaining half wouldperform the Site-Specific RiskAssessment to determine whetheremission control would be required. Therisk assessment costs were assigned tothese facilities (randomly) only if theywere not already conducting a riskassessment to demonstrate compliancewith either the metals or HCI standards.

The decision tree analysis continuedby assuming that half of the facilitiesperforming the Site-Specific RiskAssessment would pass; the other halfwould be subject to expenditures tomeet the de minimis risk levels. Asdiscussed above, this analysis did notestimate the costs of emissions controlsfor THCs, although the Agency believesthe number of facilities that would berequired to do so is small, probably lessthan ten.

Sensitivity AnalysisAs an alternative to the proposed de

minimis cancer risk level of, 1 x -10 5

EPA completed a very preliminaryanalysis of the cost impacts ofestablishing a de minimis cancer risklevel of 1x1O - . A change in theproposed de minimis cancer risk levelwould change the compliance costs formeeting the proposed metals and COstandards. The methodology used toestimate the incremental compliancecosts associated with each of thesestandards is discussed below.

Metals Standards. The metalsstandards in today's proposed rulewould necessitate expenditures in fiveareas: preliminary wastecharacterization; the Feed Rate Screen;the Emissions Screen; the Site-SpecificRisk Assessment; and APCDs. The costanalysis assumed that all facilitieswould perform the preliminary wastecharacterization and the Feed RateScreen; therefore, the alternative deminimis standard would not changethese costs. A more stringent risk-basedstandard would, however, increasecompliance costs in the other two areas.

To identify the additional facilitiesthat would fail the Feed Rate andEmission Screens under a more stringentde minimis risk level, the risk-based'Screening Limits developed by EPAwere used with one adjustment. TheScreening Limits for the carcinogenicmetals were reduced by an order ofmagnitude to reflect the X 10-

'standard. Additional facilities predictedto fail the Site-Specific Risk Assessmentwere identified.by comparing the.estimated lifetime cancer risk to the MEI

for each incinerator facility against thealternative risk level of 1 x 10- .

The incremental compliance costsassociated with more facilitiesconducting the Emission Screen and theSite-Specific Risk Assessment wereestimated using the unit cost estimatesdescribed above. An engineeringanalysis to identify the appropriateAPCD at each hazardous wasteincinerator facility failing the riskassessment has not been completed atthis time. As a result, EPA approximatedthe incremental APCD costs for twogroups of incinerator facilities:

* Facilities already failing the riskassessment at 1 X 10 -l The costing analysisassumed that to meet the 1X 1o- 6standardthese facilities would incur APCD costs atleast twice the estimated costs to meet the1XIO-a.

* Facilities failing only the 1 x 10 -

standard. The costing analysis assumed thatthese additional facilities would experienceAPCD costs similar to those estimated for thefacilities failing the I X 10-5 standard. Theaverage APCD expenditure for the proposed1 X 10-5 standard was calculated and appliedto those facilities failing only the alternativeIX 10-0 standard.There are limitations to the APCD costcalculations. For example, the costing,analysis assumes that the controlrequirements for the new facilities in theanalysis are identical to those in the1 I0- 5 analysis. In addition, thefacilities already failing the riskassessment at the proposed standardmay incur much higher APCD costs toachieve the 1 x 10- risk standard.

CO Standards. Under the health-based alternative for assessing THCemissions, a more stringent de minimisrisk standard would increasecompliance costs for facilitiesattempting to demonstrate that COemissions in excess of 100 ppm (theproposed standard) are not associatedwith unacceptable human health risks.In particular, a more stringent riskstandard would increase the number offacilities needing to complete the Site-Specific Risk Assessment (i.e., morefacilities failing Tier II) and modifycombusion practices to reduce COemissions to an acceptable level (i.e.,more facilities failing the riskassessment).

As discussed above, a decision treeanalysis was used to estimate thenumber of facilities that would besubject to incremental costs and impactsassociated with the proposed COstandards. The decision tree wasmodified to reflect the X 10- standardby increasing the probability of failingTier II and the risk assessment fromP=0.50 to P=0.75 (See Figure 3). Theincremental compliance costs

associated with more facilitiesconducting the Site-Specific RiskAssessment, as well as more facilitiesneeding to modify their combustionpractices, were estimated using the unitcosts described above.

2. Results

Proposed standards. The Agencyestimates the total annualizedcompliance costs associated withtoday's proposed requirements forexisting hazardous waste incinerators atapproximately $6.2 million. Totalincremental capital costs areapproximately $34 million; the totalincremental annual operating andmaintenance costs are roughly $3million. These nationwide costs wereextrapolated from the subset of 82facilities analyzed to the currentpopulation of 227 hazardous wasteincinerators. Capital costs wereannualized at a (historical) real discountrate of 3.7 percent over a period of 15years; one-time costs (e.g., preliminarywaste characterization costs) wereannualized over the assumed life of thepermit (ten years).

The total estimated compliance costsfor today's proposed rule aresummarized inTable 5. As shown, thepotential need for APCDs to reducechlorine and metal emissions accountsfor half of the estimated costs. Anadditional 27 percent is explained by theproposed requirements for COmonitoring and combustion of auxiliaryfuel during periods of combustion upset.The Feed Rate and Emissions Screensaccount for 17 percent of the total costs.The remining cost componentscontribute 3 percent or less to theestimated incremental compliance.

Because of substantial uncertaintiesinherent.in the accuracy of availabledata and the general nature of theengineering costing and risk assessmentapproaches utilized, the Agency urgescaution in the interpretation andapplication of these results.

Sensitivity analysis. Table 6summarizes the estimated total andincremental annual compliance costsassociated with the alternative deminimis cancer risk of I x 10- . Theincremental costs are presented againstthe baseline (i.e., before regulation) andthe proposed de minimis risk level of1X10- 5.10 4

104 In selecting a risk threshold of 10 - 6 for theserules, EPA considered risk thresholds in the range of10-' to 107 . As discussed in section I.D. of PartThree of the text, the Agency requests domnent onalternative risk thresholds.

1:7903


17904 Federal Register / Vol. 55, No, 82. Friday, April 27, 1990 / Proposed Rules

As indicated in Table 6, the morestringent risk-based standards forcarcinogens results in a higher totalannual compliance cost ofapproximately $9.7 million. This is anincrease of roughly $3.4 million over theproposed IX 10' risk standard. Almostall of the increase in cost(approximately 97 percent) can beattributed to more facilities needing tocontrol further emissions of carcinogenicmetals. In the sensitivity analysis, anestimated total of 53 existing hazardouswaste incinerator facilities (or anincrease of 22 facilities over theestimated 31 facilities requiring APCDsto meet the 1x10-5 standard) wouldneed to reduce metal emissions belowcurrent conditions.BILLING CODE 6560-SO-M


Federal Register / Vol. 55, No. 82 / Friday, April 27, 1990 / ProposedRules 17905

Table t 5-

SHiIMARY OF INCREMENTAL COMPLIANCE COSTS: PROPOSED STANDARDS

(thousands of 1986 dollars)

Number of

Percentage FacilitiesCompliance.Cost Capital and Operating and Annualized of Total Performing

Component One-lime Costs Maintenance-Costs Costs1 Annualized Costs Analysis 2

Metal StandardsPreliminary WasteCharacterization $ 717 N/A $ 87 M. 167

reed Rate Screen 1,440 N/A 175 3 167Emission Screen 4,913 N/A 596 10 131APCDs 5,980 $1,401 1,928 31 31

Subtotal $13,050 $1,401 $2,786 45%

HCL StandardsPreliminary wasteCharcterization3 $ a N/A S 0 0% 199Feed Rate Screen 3 0 N/A 0 0 199Emission Screen3 0 N/A 0 0 166APC~s 4,378 $ 811 1,197 19 45

Subtotal $ 4,378 $ 811 $1,197 19%

CO Standardstier 0. N/A $ 0 0%4 19Tier II 198 N/A 24 <1 10Modifv Combustion5 N.A. N.A. 'N.A. N.A. 5CO monitorinq 'includinqauxiliary fuel costs) 12,000 $ 620 1,657 27 227

Subtotal $12,198 $ 620 $1,699 27%4

Site-SpecificRisk Assessment6 $ 3,958 N/A $ 481 8% 98

Total $33,584 $2,832 $6,163 100%

N/A = Not applicable.N.A. = Not available.

1Capital costs were.annualized at a.(historical) real discount rate of 3.7 percent over the estimated life of theequipment 15 years). One-time costs (e.g., preliminary waste characterization) were annualized over the assumedlife of. the permit 10 years).29ased on recent information provided by HWDMS, there are currently 227 HW incinerators nationwide.

3There are no incremental costs because these tasks are already performed as part of the trial burn.4 There are no incremental cots for Tier 1, which is already performed as part of the trial burn.5A costing analysis was not completed for this category at the present time because (1) there was no availableinformation on the technical response, (2) few facilities (five) were expected to incur costs, and (3) thisproposed requirement was not expected to result in significant national 'expenditures.6These costs may apply to one or all three of the proposed standards.


17906 Federal Register / Vol. 55, No. 82 / Friday, April 27, 1990 / Proposed Rules

V-17

Table .V-t-(V

SENSITIVI[Y ANALYSIS: SUMMARY OF TOTAL AND INCREMENTAL COMPLIANCE COSTSFOR I x I0-6 DE MINIMIS RISK

(thousands of 1986 dollars)

4umber of Facilities

Annualized Cost1 Performing Analysis

2

Increment Over Increment Over

Compliance Cost I X l -.5 I X l0"

Comnent Total3 Proposed Standard Total Proposed Standard

Metal StandardsPreliminary Waste

Characterization $ 87 S 0 167 0Feed Rate Screen 175 0 167 0

Emission Screen 657 61 153 2

APCDs 5,259 3,334 53 22

Subtotal $6,178 $3,395

HCI StandardsPreliminary WasteCharacterzaztLon $ 3 S 3 199 0

Feed Rate Screenh 0 0 199 aEmission Screen4 0 0 166 0

APCOs 1,197 0 45 0

Subtotal $1,197 S 0

CO Standardstier IJ $ 0 $ 0 227 0

Tier I 24 10 19 9

Modify Combustion5

N.A. N.A. 11 6

CO onitoring includinqauxiliary Fuel costs) 1,676 0 227 0

5ubtotal $1,702 $ 10

Site-Soecific

Risk Assessment, $ 572 $ 92 :34 36

'OtAL $9,650 $3,487

N.A. = Not available.

lincludes annual OM coats, if any, plus annualized capital or other one-time cost(s). Capital

Costs were annualized at a (historical) real discount rate of 3.7 percent over the estimated life

of the equipment (15 years). one-time costs (e.g., preliminary waste characterization) were

annualized over the assumed life of the permit '10 years).29ased on recent information provided by HWD3S, there are currently 227 facilities with one or more

HW incinerators nationwide including Puerto Rico.3total capital costs for all requirements in the sensitivity analysis were approximately

$45 million (roughly $11 million more than the total capital costs estimated for compliance with a

I x I0-5 de minimis risk standard). Total O&M costs were approximately $5.3 million (roughly

$1.5 million more than the total O&M costs estimated for compliance with a I 4 105 de minimia

risk standard).

41here are no incremental costs because these tests are already performed as part of the trial

burn.5There are no incremental costs for fier 1, which is already performed as part of the trial burn.

6A costing analysis was not completed for this category at the present time because (1) there was

no available information on the technical response, (2) few facilities (five) -ere expected to

incur costs, and (3) this proposed requirement was not expected to result in significant national

e.penditures.7these coats may apply to one or all three of the proposed standards.

BILUNG CODE 6560-50-C



D. Economic Impact Analysis

A preliminary economic impactanalysis was conducted for the subset offacilities evaluated from the Mail Surveybased on the compliance costs for theproposed and alternative (sensitivityanalysis) standards described above.Results were also extrapolated to thepopulation of existing hazardous wasteincinerators. The methodology andresults of this analysis are detailedbelow.

1. Methodology

Based on a review of alternativeanalytical approaches and availablefinancial data, first order economicimpacts were approximated bycalculating (1) the ratio of annualincremental compliance costs to averagegross profit before tax and (2) the ratioof annual incremental compliance coststo the average cost of production foraffected facilities at the four-digitindustry level of the standard industrialclassification (SIC) system. These ratioswere used to identify the potentialincrease in production price and thereduction in gross profitability foraffected industries resulting fromcompliance with the proposedrequirements.

Implicit in the ratio calculations is theassumption that each facility absorbsthe costs of compliance. Although thedecision to pass through costs is afunction of market response (i.e., theprice elasticity of demand for thefacility's product], this effect could not

be quantified because of time andresource constraints. However, theassumption that all costs would beabsorbed will provide, in general, aconservative estimate of predictedimpact. This is particularly conservativefor commercial hazardous wasteincinerators which, given the seeminglyextreme inelastic demand forincineration capacity in recent years,will probably be able to pass theincremental compliance costs through tothe customer.

The average cost of production andgross profit at the four-digit SIC codelevel were calculated using data fromthe 1984 U.S. County Business Patternsand the 1984 Annual Survey ofManufacturers. In particular, thesesources were used to derive an estimateof average net cash flow fromoperations (CFO), taken as a crudemeasure of gross profit, and averagecost of production (COP) at the four-digit SIC level.

The financial ratio analysis wasperformed on a facility basis using onlyaverage industry financial data. It wasimpossible to consider variability infinancial impact by plant size,productivity or other measure of impactbecause the necessary data were notavailable within the scope of this effort.The use of average industry data couldsubstantially understate adverse impactfor some individual facilities.

Using the annualized compliancecosts estimated for each facility and theaverage industry financial data, the two

financial ratios described above werecalculated to assess impact. Adverseeconomic impact was indicated if either(1) the compliance costs increasedproduction costs by more than I percentor (2) compliance costs accounted formore than 1 percent of net cash flowfrom operations. These thresholds aremore conservative than those used inmany recent EPA analyses. Generally,EPA has identified significant impactwhen either the ratio of compliancecosts to COP or the ratio of compliancecosts to CFO is greater than 5 percent..

2. Results

Proposed standards. Table 7summarizes the distribution of economicimpact for each of the financial ratioscalculated. As shown, the proposedregulations will not impose an undueeconomic burden on the majority of allhazardous waste incinerator facilities.Based on the COP ratio, 6 percent of allhazardous waste incinerator mayexperience adverse economic impactsbecause of predicted average increasesin production costs between 1 percentand 2 percent. The CFO ratio indicatesthat approximately 12 percent ofhazardous waste incinerators maywitness decreases in their grossprofitability ranging between 1 percentand 4 percent. None of the calculatedfinancial ratios exceeds 4 percent or the5 percent hurdle rate generally used byEPA to determine significant impact.

TABLE 7.-DISTRIBUTON OF ECONOMIC IMPACT: PROPOSED STANDARDS

Number of Affected Entities with Hazardous Waste Incinerators

Impact ratio 0-0.99 1-1.99 2-2.99 3-3.99 4-4.99percent percent percent percent Percent Total(")

Cost of compliance/cash flow from operations ............................ 199 (88%) 11(5%) 14 (6%) 3 (1%) 0 227 (100%)Cost of compliance/cost of production ......................................... 213 (94%) 14 (6%) 0 0 0 227 (100%)

Numbers may not sum because of rounding.

Table 8 presents the distribution of facilities in four SIC categories. The although there are higher predictedeconomic impact by SIC for those CFO ratio indicates impact for almost impacts for SIC 2873 (Fertilizers,facilities exceeding the 1 percent twice as many facilities distributed Nitrogenous).threshold. The COP ratio shows among nine different SIC codes. No onepotential significant impact for 14 SIC category appears to dominate,

TABLE 8.-Distribution of Economic Impact by SIC: Proposed Standards 1

Number of Affected Facilities

Cost of compliance/cash flow from operations Cost ofcompliance/

cost ofSIC 1-1.99 2-2.99 3-3.99 production

percent percent percent 1-1.99percent

2421 (Saw mills and planing mills).2511 (Wood household furniture)...

............................................................................................................ I ................... i.......

..........................................................................................................

1790717907

3 .........................3


17908 Federal Register / Vol. 55, No. 82 / Friday, April 27, 1990 / Proposed Rules

TABLE 8.-Distribution of Economic Impact by SIC: Proposed Standards 1-ContinuedNumber of Affected Facilities

Cost of compliance/cash flow from operations Cost ofcompliance/

cost ofSIC 1-1.99 2-2.99 3-3.99 production

percent percent percent 1-1.99percent

2813 (Industrial gases) ......................................................... ..................................................................................................... 3 .............................32821 (Plastics m aterial) ................................................................................................................................. .....................................................................................2851 (Paints and allied products) .................... ............................................................................................................... 3 ............................. 32873 (Fertilizers, ntitr ogeneou s) .................................................................................................................... .......................... 6 .............................3229 (Gases) .................................................................................................................................................

3672 (Cathode ray picture tubes TV) ...................................................................................................................................... 3 .............................39999 (Nonclasslflable establishments) ........................................................................................................ 3 .......... .......... .......................

Total facilities s ................................................................................................................................... 11 14 3 14

'Results are summarized only for those facilities exceeding the 1 percent threshold for each calculated financial ratio.' Numbers may not sum because of rounding.

Sensitivity analysis. The results of the representing between 1 percent and 4 representing more than 4 percent offinancial ratio tests for the sensitivity percent of production costs. The CFO either net cash flow or production costs,analysis are summarized in table 9. ratio calculations indicate a larger an estimated 6 facilities could faceSimilar to the results for the proposed fraction of facilities (39 facilities or compliance costs that are greater than 6standards, the majority of facilities are roughly 17 percent of the total percent of net cash flow. Table 10not predicted to incur adverse economic population) that could be subject to presents the distribution of economicimpact. Based on the COP ratio results, adverse financial conditions if the impact by SIC for those facilitiesan estimated 20 facilities (approximately proposed requirements are enacted. exceeding the 1 percent threshold.9 percent of the total population) would Although most of these 39 facilities areface incremental compliance costs not predicted to incur compliance costs

TABLE 9.-Distribution of Economic Impact: Sensitivity Analysis

Number of Affected Entities with Hazardous Waste Incinerators (percent of total)

0-0.99 1-1.99 2-2.99 3-3.99 4-4.99 5-5.99 6-6.99 TotalImpact ratio percent percent percent percent percent percent percent

Cost of compliance/cash flow from operations .................... 188 22 0 11 0 0 6 227

Cost of compllance/cost of production .................... 207 11 6 3 0 0 0 227

Numbers may not sum because of rounding.

TABLE 10.-Distribution of Economic Impact by SIC: Sensitivity Analysis 1

Number of Affected Facilities

Cost of compliance cash flow from operations Cost of Compliance Cost ofProduction

SIC 1-1.99 2-2.99 3-3.99 4-4.99 5-5.99 6-6.99percent percent percent percent percent percent 1-1.99 2-2.99 3-3.99.percent percent percent

2421 (Saw mills and planing mills) ...................... ....... 3 ...........................................................................................................................................................2511 (W ood household furniture) ................... 6 .................................................................................................................................................................................2813 (Industrial gases) ................................... ............................................ 3 .................................................... ............................................................ 32819 (Inorganic chem icals) .............................. 3 ...............................................................................................................................................................................2821 (Plastics material) ..................................... 3 . ........................ ...........................................................................................................................2851 (Paints and allied prod ucts) ............................................ 3 ....................................................................................... 3 ...........................................2873 (Fertilizers nitrogeneous) ......................................................................................... .... 6 ...................... 6 .....................2879 (Pesticides) .............................................. 3 ............................................................................................................... 3 .........................................3229 (G ases) ....................................................... 3 ................... ............ .................... ....................... ............... ....... 3 ...................... .....................

3339 (Prim ary sm elting) .................................... 3 .................. ................................ ................................................................................................3672 (Cathode Ray picture tubes TV) .................... . ..... ...................................................... 3 ..... .............9999 (Nonclasslflable establishments) ............ 3.................. ...................................................

Total facilities ........... ....... 22 0 11 0 0 6 11 6 3

'Results are summarized only for those facilities exceeding the 1 percent threshold for each calculated financial ratio.*Numbers may not sum because of rounding.



F. Risk Assessment

1. Methodology

A comparative risk assessment wasperformed under existing baseline andpost-compliance conditions for the 82hazardous waste incinerator facilitiesevaluated from the Mail Survey, andresults were assessed considering boththe proposed de minimis cancer riskstandard of 1 X 10-5 105 and thealternative standard of 1 X 10-6evaluated in the sensitivity analysis.The risk assessment was performed forboth metals and HCL, but there wasinsufficient information to quantifyeither the baseline or controlled humanhealth risks posed by total residualhydrocarbons at the present time.

For the carcinogenic metals analyzed(arsenic, cadmium, and hexavalentchromium), two measures to risk wereestimated: lifetime cancer risk to themaximum exposed individual (MEI) andthe annual cancer incidence attributableto all metals at each facility. For thenoncarcinogens evaluated (HCI, lead,barium, and mercury), the Agencyidentified which facilities may presentan increased likelihood of noncancereffects by exceedances of healththreshold limits, but the total number ofcases could not be calculated for thesepollutants. Throughout, EPA's riskestimates considered exposure throughinhalation only; other exposures (e.g.,ingestion) were not evaluated.

To estimate the lifetime MEI cancerrisks and any exceedances ofacceptable Reference AirConcentrations (RACs), data wereneeded on the following: the quantity ofHCI and metals emitted by eachhazardous waste incinerator facility; apoint estimate of the maximum ambientair concentration outside the fencelineof the incinerator facility; and pollutant-specific health rish factor (either unitcancer risk numbers developed byEPA's Carcinogen Assessment Group orthe RACs for noncancer effects). These

'data were also used in the variousscreening analyses described above todemonstrate compliance with theproposed HCI and metals standards. Topredict the incidence of cancer, twoadditional pieces of information wererequired: estimates of the ambient airconcentrations over a 50 km falloutradius from the facility, and estimates ofthe number of exposed persons at thevarious emission concentrationsthroughout the fallout area. The steps

105 In selecting a risk threshold of 10 -3 for these

rules, EPA considered risk thresholds in the range of10-' to 10- . As discussed in section I.D. of PartThree of the text, the Agency requests comment onalternative risk thresholds.

taken to gather the necessary data forthe risk assessment are detailed below.

Emissions (metals). EPAapproximated metals emissions byfacility utilizing estimates of (1) thequantity of hazardous waste combustedby RCRA code, (2) the estimatedfraction of metals in each RCRA code,(3) the fraction of each metal segregatedas bottom ash and stack emissions, and(4) metal removal efficiencies for in-place APCDs.

EPA obtained data on the quantity ofhazardous waste combusted by RCRAcode from the Mail Survey. The toxicconstituent profiles for each RCRA codewere developed by EPA using readilyavailable information from severalsources, including the W-E-T model andvarious sampling efforts conducted bythe Agency to develop the toxicconstituent profilesA0 6 Wastecharacterization data by RCRA codecould not be located for thallium,antimony, and silver, therefore, thesepollutants could not be addressed in thisanalysis. In addition, this analysis couldcharacterize only the fractions of totalchromium by RCRA code. Based onavailable results from recent andongoing analyses of combustion sources,EPA assumed for the present that Ipercent of total chromium waste feedand stack emissions would be of thehexavalent (carcinogenic) species andthat the remaining 99 percent would betrivalent.' 07 It was assumed that allwaste streams are combustedsimultaneously on an annual averagebasis because of limited data on thistopic.

To quantify total annual toxic metalsemissions for each facility, EPAcombined the estimated quantities ofeach metal combusted annually at eachincinerator analyzed in the Mail Surveyand engineering estimates onpartitioning and removal efficiencies ofin-place APCDs by metal. The APCDremoval efficiencies were quantified bypollutant for each hazardous wasteincinerator using the best engineeringjudgement and information on inplacecontrols from the Mail Survey.

10a The sampling efforts included: Versar,"Hazardous Waste and Virgin Oil Assessment ofBaseline Metal Content," April 1988; Mitre,"Hazardous Waste Stream Trace MetalConcentrations and Emissions," 1983; and Environ,"Characterization of Waste Streams Listed in 40CFR Section 261," 1983. These particular studieswere selected because they reported pollutantconcentrations by RCRA code.

107 Analysis conducted by EPA's Office of AirQuality Planning and Standards (coal-fired boilers)and Office of Water (sludge incineration). However,more recent tests of hazardous waste combustionindicate that hexavalent chromium may representas much as 10% of the total chromium emissions(see Part Three, 11.B. of today's preamble).

Partitioning coefficients were developedby pollutant for solid waste incineratorsto estimate the proportion of metalssegregated as bottom ash and stackemissions. The analysis assumed thatthere is no partitioning in liquidinjectors (i.e., all metals are vaporized).

Emissions (HCI. To estimate HCIemissions, EPA collected information onthe same critical elements used in theassessment of metals emission rates(i.e., quantity of hazardous wastecombusted by RCRA code, partitioning,and removal efficiencies of inplace(APCDs). The waste data by RCRA codewere obtained.from the Mail Survey.

To approximate the quantity ofchlorine incinerated, EPA first identifiedRCRA codes that could potentiallycontain chlorine. This list of RCRAcodes was compiled by (1) reviewingwaste sampling data (by RCRA code) ina supporting document to the existingRCRA regulations for hazardous wasteincinerators and (2) identifyingadditional RCRA codes that couldcontain chlorine based on their wastecharacteristics. ' 08

To determine the chlorine content,EPA calculated the average (arithmetic)chlorine concentration in all wastecombusted in hazardous wasteincinerators using available test bumdata (89 data points) for 23 incineratorsunits located throughout the UnitedStates.' 09 The total quantity of chlorinebeing combusted was calculated bymultiplying the quantity combusted ofRCRA codes potentially containingchlorine at each incinerator by theestimated average chlorine level(roughly 8 percent). A more detailedanalysis of chlorine was not performedin this analysis because of time andresource constraints.

IIC1 emissions were calculatedassuming that all chlorine converts toHCI. In addition, the removalefficiencies afforded by in-placecontrols were considered. The analysisassumed that no partitioning wouldoccur for HCI (i.e., all HCI formed duringthe combustion process would beemitted as a gas). The analysiscalculated emissions by assumingconservatively that all waste typesreported in the Mail Survey would be

1aS USEPA. Waste Treatment Branch, Office ofSolid Waste and Emergency Response. "SupportingDocumentation for the RCRA IncineratorRegulations. 40 CFR 264, Subpart 0 Incinerators,"Peer Consultants. Inc. for the Office of Solid Wasteand Emergency Response. October 1984. (NTISorder No. PB86-110293)

1as USEPA. Office of Research and DevelopmentCenter for Environmental Research Information,"Handbook Permit Writer's Guide to Test BurnData, Hazardous Incineration." EPA-625/6-86/012.

1790917 nqP



combusted simultaneously on an annualaverage basis. This assumption couldresult in an underestimate of thepotential risks from short-termexposures, as well as compliance costs.

Ambient Concentrations (Metals andHCI). EPA predicted maximum andarea-wide ambient concentrations of themetals and HCI emitted from eachfacility using dispersion modeling. Itwas outside the scope of this analysis toestimate maximum ambientconcentration performing site-specificdispersion modeling. As a result, thisanalysis used the predicted ambientconcentrations generated from 10hypothetical facilities evaluated at eachof 24 sites, which were located in widelyvarying terrain (see the discussion inPart Three of today's proposed rule).1 10

EPA performed the dispersion modelingusing 16 wind directions and 15 ringdistances, ranging from 0.2 km to 50 kIn.Ambient concentrations were estimatedseparately for long-term and short-termexposures.

Health Risk Factors. The unit cancerrisk values were provided by EPA'sCarcinogen Assessment Group and arelisted in Appendix B of today's proposedrule. The RAC's for the noncarcinogenswere provided by EPA's Office of SolidWaste and are also summarized inAppendix B of today's proposed rule.The RACs represent 25 percent of theReference Doses (RfDs) for all pollutantsexcept lead; existing background levelsare assumed to account for theremaining 75 percent of the RfD. Thelead RAC is defined as 10 percent of theNational Ambient air Quality Standard(ANAQS) that has been promulgated forlead under the Clean Air Act;background exposures take up theremaining 90 percent of the NAAQSstandard. These risk factors consideronly long-term effects and incorporatestandard EPA exposure assumptions(e.g., the average exposed individualwill weigh 70 kg, will inhale 20 cubicmeters of air each day, and will beexposed continuously to the estimatedambient pollutant concentration for 70years).

Population Exposed. Data on thenumber of exposed individuals in thevicinity of each facility analyzed wasobtained from U.S. Census data

10 Detailed information on the dispersioncoefficients used in the risk assessment can befound in: Memorandum from Versar to TBS."Modeling Summary of Flat and Rolling TerrianIncinerator Sites." May 20.1987; Memorandum fromVersar to TBS. "Modeling Summary of the HighTerrain Incinerator Site," June 12. 1987;Memorandum from Versar to TS, "ModelingResults of Short-Term MEI Concentrations forHazardous Waste Incinerators", July 15, 1987.

available from the Office of ToxicSubstances' Graphical ExposureModeling System (GEMS). Thepopulation data were first obtained inthe block grid/enumeration district leveland then summed to correspond withthe geographic segments used in thedispersion modeling.

2. ResultsProposed Standards. Table 11 shows

the Agency's estimates of the effect oftoday's proposed rule on MEI cancerrisk levels for metals at metal-burningincinerators. The highest lifetime cancerrisk estimated in the baseline is roughly5.0 X 10 - 5, with approximately 22 sites(13 percent of all facilities burningmetals) posing risks within this 10- 5range under baseline conditions. Theremaining 87 percent are estimated to becurrently operating under conditionsposing less than a one in 100,000 lifetimerisk of causing cancer to the maximumexposed individual. The principal effectof today's rule as it relates tocarcinogenic metals would be to causean estimated 22 facilities to reduce theiremission rates to levels at or below the 1X 10-5 risk level.

The estimated annual baseline cancerincidence for the three carcinogenicmetals, aggregated across all 167 sites atwhich EPA estimates such metals areburned, is approximately 0.03 or roughlytwo cases in 70 years nationwide. Theincidence results in a given year aresummarized in Table 12 by pollutant. Asshown, hexavalent chromium accountsfor over half of the predicted annualcancer incidence, with cadmium andarsenic contributing approximately 34percent and 13 percent, respectively.

TABLE 11.-DISTRIBUTION OF INCINERA-TOR FACILITIES BY ESTIMATED LIFETIMEMEI CANCER RISKS FOR INCINERATORSBURNING METAL-BEARING WASTES: BE-FORE AND AFTER COMPLIANCE 1

Number of HW incineratorLifetime MEI facilities (percentage of total) Icancer risks After

Baseline compliance

1.00E-02 ................. 0 01.00E-03 ................. 0 01.OOE-04 ................. 0 01.OOE-05 ................ 22 (13%) 01.00E-06 ................. 28 (17%) 50 (30%)1.00E-07 ................ 47 (28%) 47 (28%)1.00E-08 ................. 36 (22%) 36 (22%)1.00E-09 ................. 20 (12%) 20 (12%)1.00E-10 ................. 8 (5%) 8 (5%)1.00E-11 ................. 3 (2%) 3 (2%)1.00E-12 ................. 3 (2%) 3 (2%)

Total facilitiesburningmetalss ........... 167-(100%) 167-(100%)

I Results for three metals: arsenic, cadmium, andhexavalent chromium. Compliance based on meetinga 1.00E-05 MEI cancer risk leveL

' Based on available information. EPA estimatesthat 167 or about 75 percent of the 227 facilitiesbum metal-beaing wastes.

' Numbers may not sum to total because ofrounding.

TABLE 12.-ESTIMATED EXCESS ANNUALAND LIFETIME CANCER INCIDENCE FORINCINERATORS -BURNING METAL-BEAR-ING WASTES BEFORE AND AFTER COM-PLIANCE z

Number of cases prCases per 70year (Prmtage of years

total)Pollutant

-After.Baslin Afer ase- Complance I o c

Arsenic ......... 0.005 (13) 0.003 0.318 0.184Cadmium..... 0.012 (35) 0.007 0,824 0.509Chromium

(VI) ........ 0.018 (52) 0.009 1.248 0.603

Total' 0.034 0.019 2.39 1.297

'Compliance based on meeting a 1.00E-05 MElcancer risk level.

'Numbers may not sum because of rounding.

After compliance with the proposed1 X 1075 de minimis cancer risk level forindividual sites, EPA conservativelyestimates that the annual cancerincidence for these incinerated metalscould be reduced from 0.03 to 0.02, or areduction from approximately twolifetime cancer cases to one lifetimecancer case nationwide in a 70-yearperiod. These calculations were basedon the risk reduction needed to meet theproposed risk-based standards and mayhave been understated. The actualenvironmental protection afforded bythe recommended control technologiesat each affected facility could be higher.

The risk assessment also estimatedexceedances of the RACs for lead andHC1 (short-term and long-term). Thepredicted ambient air concentrations ofthe other noncarcinogenic pollutantsanalyzed (barium and mercury) did notexceed the RACs for these twopollutants at any of the sample facilitiesmodeled. Table 13 summarizes thenumber of incinerator facilities forwhich exceedances of the lead and HClRACs are estimated. It also slows therange of estimated percent reductions inemissions necessary for these facilitiesto meet the RACs. The number ofexceedances is highest for HC1 (short-term effects), followed by lead. There isalso overlap among the facilities failingthe lead or HCI RACs. Approximately 22

1791017910



of the 48 facilities are exceeding boththe lead and short-term HC1 RACs. Allof the facilities not complying with thelong-term HC1 RAC are also exceedingthe lead RAC. Under 100 percentcompliance with the proposed risk-based standards for lead and HCI, therewill be no exceedances of the RACs.

TABLE 13.-ESTIMATED INCREASED LIKE-LIHOOD OF NONCANCER EFFECTS: Ex-CEEDANCES OF THE LEAD AND HCLRACS BEFORE AND AFTER COMPLIANCE

Number of NW Percentincinerator reduction

facilities inexceeding the emiSsions

Pollutant RAC neces-

Base- After sar toline compli- comly

ance

Lead. ............. 31 0 19-91HC (short-term)1 48 0 5-78HCI (long-term) 2 18 0 20-99

22 of the 48 facilities do not comply with eitherthe lead or the short-term HCI standard.

2 All of the facilities unable to comply with HCIstandard also do not comply with the lead standard.

Sensitivity Analysis. The alternativede minimis risk standard evaluated inthe sensitivity analysis (1 X 10- 9 willhave an impact only on the cancer riskestimates for metals. Table 14 shows theAgency's estimate of the effect of thealternative standard on MEI cancer risklevels for metals at metal-burningincinerators. The more stringentstandard would cause an estimated 50facilities to reduce their emission ratesfor carcinogenic metals to levels at orbelow a 1 X 10- risk level. This is anincrease of 28 additional facilities abovethe proposed standard; however, six ofthese facilities are already predicted toneed controls to reduce emissions ofnoncarcinogenic metals.

As discussed above, the estimatedannual baseline cancer incidence for thethree carcinogenic metals, aggregatedacross all 167 sites at which EPAestimates metals are burned, isapproximately 0.03 or roughly two casesnationwide in 70 years (see Table 15). Amore stringent de minimis risk standardof 1 X 10- 6 would lower the estimatedannual cancer incidence toapproximately 0.01 or about one casenationwide in 70 years. These aftercompliance calculations were based onthe percent reduction in emissionsneeded to meet the alternative risk-based standard.

TABLE 14.-DISTRIBUTION OF INCINERA-TOR FACILITIES BY ESTIMATED LIFETIME

MEI CANCER RISK FOR INCINERATORSBURNING METAL-BEARING WASTES: BE-FORE AND AFTER COMPLIANCE 1

Number of HW incineratorfacilities (percentage of

Aggregate lifetime MEI total)p

cancer rsksBaseline ace____ ___ ___ (percent)

1.00E-02 ......................... . 0 01.00E-03 .......................... 0 01.00E-04 .......................... 0 01.00E-05 .......................... 22(13) 01.00E-06.... .... 28 (17) 01.00E-07 .............. 47 (28) 97 (58)1.00E-08 .......................... 36 (22) 36 (22)1.00E-09 .......................... 20(12) 20,(12)1.00E-10 .......................... 8(5) 8 (5)1.00E-1 1 ..................... 3(2) 3(3)1.00E-12 ......................... 3 (2) 3 (3)

Total facilitiesburning metals (3) 167 (100) 167 (100)

'Results for three metals: arsenic, cadmium, andhexavalent chromium. Compliance with a 1.00E-06risk standard (sensitivity analysis).

2 Based on available Information, EPA estimatesthat 167 or about 75 percent of the 227 facilitiesbum metal-burning wastes.

3 Numbers may not sum to total becauseof round-Ing.

TABLE 15.-ESTIMATED EXCESS ANNUAL

AND LIFETIME CANCER INCIDENCE FOR

INCINERATORS BURNING METAL-BEAR-ING WASTES: BEFORE AND AFTER COM-

PLIANCE 1

Number of cases per year Cases per 70(percentage of total) years

Baseline After Base- AfterPollutant (percent) compli- line Com-

ance pliance

Arsenic ......... 0.005 (13) 0.001 0.318 0.103Cadmium 0.012(35) 0.004 0.824 0.299Chromium

(VI) ............ 0.018 (52) 0.005 1.248 0.368

Total '. 0.034 (100) 0.011 2.39 0.771

3Compliance based on meeting a 1x10-6 MEIcancer nsk level.2 Numbers may not sum because of rounding.

G. Regulatory Flexibility Analysis

The Regulatory Flexibility Act (RFA)requires Federal regulatory agencies toevaluate the impacts'of regulations onsmall entities. This section summarizesEPA's methodology for conducting apreliminary RFA analysis and theresults of that analysis. Based on theresults, EPA has determined that today'sproposed rule will not have a significantimpact on a substantial number of smallentities. For the purpose of this analysis,EPA assumed that all facilities weresingle-established businesses/entities.

1. Methodology

The results of the economic impactanalysis were used as the basis for the

RFA analysis. Those facilities exceedingthe I percent threshold for bothfinancial ratios calculated (COP andCFO) were the primary focus of theRFA. The analysis was performed forthe subset of 82 facilities selected fromthe Mail Survey; the results wereextrapolated to the population of 227entities operating hazardous wasteincinerators.

EPA first identified which of the 82hazardous waste incinerator facilitiesevaluated in the Mail Survey could bedesignated as small business entities. Inparticular, EPA used the sales data inWard's Business Directory to determinewhich hazardous waste incineratorswere owned by entities that couldreasonably be classified as large.Ward's lists all companies with annualrevenues greater than $10 million. EPAsubjectively identified all entities listedby Ward's as "large." In addition, EPAdetermined whether an entity couldreasonably be classified as "large" inthe absence of financial data, e.g., auniversity. If an entity could not beclassified as "large" on the basis ofeither Ward's or by inspection, EPAassumed it was a "small" entity.

EPA then identified whether thepotentially affected "small" entitiesaccounted for a significant percentage ofall small entities owning hazardouswaste incinerators, or a significantpercentage of all small entities within a* given SIC code (i.e., industry). The totalnumber of entities identified as "small"for each SIC code was determined usingthe SBA small plant employee size cut-offs and information from the U.S.Census on the distribution of facilitiesby employee size within each SICcategory. As a general criterion, the EPAconsiders a proposed rule to have asignificant impact on a substantialnumber of small entities if 20 percent ofsmall entities covered by the rule aresignificantly affected by today'sproposed rule.

2. Results

The majority of entities owninghazardous waste incinerators (202facilities, or 89 percent of all facilities)were designated as "large," as shown inTables 16 and 17. The entities owningthe remaining 25 facilities wereidentified as "small." The "large"entities were predicted to incur'approximately 87 percent of theestimated annualized compliance costs(roughly $5.4 million) associated withthe proposed standards, andapproximately 90 percent of theestimated annualized costs (roughly $8.6million) associated with the alternativestandards evaluated in the sensitivity

17911


17912 Federal Register / Vol. 55, No. 82 / Friday, April 27, 1990 1 Proposed Rules

analysis. It is important to note that thedesignation of a facility as a "smallentity" was based on a preliminaryreview of readily available information.However, this outcome appearsplausible from the standpoint that onlylarger industrial operations would find iteconomically feasible to construct andoperate on-size hazardous wasteincinerators.BILLING -CODE 6560-"



VI-11

Table *1-/(

DISTRIBUTION OF COMPLIANCE COSTS BY FACILITY SIZE AND SIC

Large EntitiesNumber o..

Numb'er of

Facilities

3

336

38

20333

333

820'611

3

66

3.3.

SICCode

223122822421249125112661281328192821

2822282428332834.28442851286128652869287328792891

2892289929113079322933393412343334663483353136723721495373918062

822196619999;

Tot

ComplianceCosts '

$ 15,069

34,18413,28568,20228,567139 ,624235,860324,29827,93030,99282,272258,781131,017163,80530,139

210,607223,480

1,609,572218,067.25,463

18,40552,33790,874

127,033137,803

27,90449,77697,64682,562170,46517,006196,612

134,78527,43834,98716,131

207,004

$5,359,981

Small Entities

Number of ComplianceFacilities Costs

SS i5,685

516,640

15,069

91',96112,893

15,989

13,525

25,301.

38,434

$805,498

ISums may not total because of rounding.

3333331814

63

a11 , 202

1791317913


Federal Register / Vol. 55, No. 82 1 Friday, April 27, 1990 / Proposed Rules

VI-12

Table Vt-7 /7

DISTRIBUTION OFCOMPLIANCE COSTS BY FACILITY SIZEAND SIC: SENSITIVITY ANALYSIS

Large Entities

Number ofFacilzties

3

33

633820

3333333820611

3366

33

SICCode

223122822421249125112661281328192821282228242833283428442851286128652869287328792891

289228992911307932293339341234333466

34833531

367237214953

73918062

822196619999

Tot

ComplianceCosts

$ 15,069

34,18413,28576,76631,115

224,901390,758538,63936,49350,66782,272322,577197,452282,21230,139

219,170424,244

2,884,366

395,89825,46318,40576,968

257,594

215,004292,701

27.,90449,776121,48686,809296,26225,570

217,108312,61627,438

52,11316,131

274,389

$8,643,945

Small Entities

Number of ComplianceFacilities Costs

$ 15,685

576,640

15,069

267,24412,893

15,989

13,525

48,234

38,434

$1,003,714

ISums may not total becaue of rounding.

BILUNG CODE 6560-50-C •

3333331814

3638

all 202

17914



The COP ratios did not exceed the 1percent threshold for any of the entitiesidentified as "small" considering eitherthe proposed or alternative standards(see Table 18). The CFO ratio was inexcess of 1 percent for only three"small" entities in SIC 2821 (with noneexceeding 2 percent) for the proposedstandards. These three entities representapproximately 12 percent of all "small"entities owning and operating hazardouswaste incinerators and 1 percent of alldesignated small entities within the 2821SIC Code.111

TABLE 18.-SMALL PLANT IMPACTS:FINANCIAL RATIO TESTS

Estimated nationwide smallentities operatinghazardous waste

incinertors (1)Analytical scenario Cost of Cost of

oompli- compli-ance/ anc/

COP>1% CFO>1%

A. ProposedStandardsSIC 2821 .............

Total ..........................S. Sensitivity Analysis:

SIC 2821 ......................SIC 2865 ......................

0

0

00

Total ......................... 0

COP =Cost of Production.CFO=Cash flow -from operations.(1) There is an estimated total of 25

operating harzardous waste incinerators

In the sensitivity analysis, anestimated six small entities wepredicated to face incrementalrepresenting between I percenpercent of net cash flow. Theseentities account for approximapercent of all small entities opehazardous waste incinerators.this appears to represent a subnumber of small entities (i.e., gthan 20 percent), it is importanthat the CFO ratios for these srentities never exceed 2 percent

Based on these results, EPAthat the today's proposed ruleprobably not pose a significanteconomic impact on a substantnumber of small entities.

H. Paperwork Reduction Act

The information collectionrequirements in this proposedbeen submitted for approval tcOffice of Management and Bu

it I is important to note that the pe

small entities in SIC 2821 and 2865 affetoday's proposed rule could be underesMany of the entities in each SIC assurnsmall based on employee size may hayannual revenues or be owned by largecompanies. This determination could nusing available data.

(OMB) under the Paperwork ReductionAct, 44 U.S.C. 3501 et seq. Reporting andrecordkeeping burden on the public forthis collection is estimated to average628 hours per responser for reportingand 20 hours per response forrecordkeeping.

If you wish to submit commentsregarding any aspect of this collection ofinformation, including suggestions forreducing the burden, or if you would likea copy of the information collectionrequest (please reference ICR #1559),contact Rick Westlund, InformationPolicy Branch, PM-223, U.S.Environmental Protection Agency, 401 MSt., SW., Washington, DC 20460 (202-382-2745); and Marcus Peacock, Officeof Information and Regulatory Affairs,Office of Management and Budget,Washington, DC 20503. The final rulewill respond to any OMB or publiccomments on the information collectionrequirements contained in this proposal.

IlL Pollution Prevention Impacts

These amendments would provide an3 (1.6%) incentive to reduce the generation of

3 metal and chlorine-bearing hazardouswaste at the source given that the

3 (1.6%) proposed metals and HCl emissions3 (1.0%) controls would be implemented by

6 additional requirements attendant to thedisposal of those wastes, i.e., incineratorfeed rate limits for individual metals and

small entities total chlorine. These requirements are,in essence, tied to the economics ofdisposing of given volumes of waste

re since feed rates depend, in part, on there volume of waste the incineratorcosts

and 2 operator needs to burn. Thus, the metals

six small and HCI controls proposed in this rule

tely 24 do not simply require a percenterely 24 reduction in emissions, irrespective ofrating the volume and rate of incoming waste

While streams. Rather, the controls are health-stantial based and, thus, provide limits on

reatert to recall emissions rates of metals and HCI thatmall would be implemented by feed ratea. limits.

concludes Waste generators who send their

will waste to commercial incinerators would

adverse have the incentive to reduce the

tial generation of metal and chlorine-bearingwastes because incineration fees arelikely to increase for such waste giventhat the incinerator has a fixed metaland chlorine feed rate allotment (due to

rule have prescribed feed rates and incineratoro the operating conditions). Wastes withdget extremely high metals content may no

longer be acceptable for incineration in

rcentage of many cases unless the waste generatorcted by reduces the metals content of the waste.timated. Any alternative for the disposal of suchaed to be wastes may be unavailable or the costsa large of such treatment may be high enough toholdingot be made create the incentive to reduce waste

generation rates at the source. This is a

typical scenario for pollution preventionmeasures to be undertaken by wastegenerators.

Similarly, generators who incineratetheir wastes on site also have theincentive to reduce the generation ofmetal and chlorine-bearing wastes giventhat the proposed rule would provide afixed feed rate allotment for theirincinerator.

List of Subjects in 40 CFR Parts 260, 264,and 270

Hazardous material, Incorporation byreference, Packaging and containers,Reporting and record keepingrequirements, Security measures, Suretybonds, Waste treatment and disposal,Administrative practice and procedure,Confidential business information,Harzardous materials transportation,Hazardous waste, Water pollutioncontrol, Water supply.

Dated: April 9,1990.William K. Reilly,Administrator.

Appendix A-Measurement of Metalsand Hydrogen Chloride

A-1: Metals Measurement MethodsGeneral considerations of sampling

wastes for metals, the digestion of thecollected samples, and the analysis ofthe resulting solution are described inChapter 3, Volume 1A of "Test Methodsfor Evaluating Solid Waste, Physical/Chemical Methods," EPA PublicationSW-846 (incorporated by reference in§ 260.11). The current methods aresummarized below in Tables A-1 andA-2.

TABLE A-1 .- SAMPLE PREPARATIONMETHODS

Methods Analysis procedure Waste matrix

3010 ICP, FLAA .................. Aqueous only.3020 GFAA ........... _ Aqueous only.3050 FLAA, ICP or Sediment, sludge,

GFAA. soil, filterparticulatematerial, andfilter from stacksampling train.

3040 ICP or FLAA.. .......... Oils, greases orwaxes.

Method 3040 is only recommended for virgin oilor clean used otis. It Is not recommended for oilthat contain emulsions and particulates. Until EPA'microwave digestion technique is available, use thHNOs/H2O combination and procedure frorMethod 3050 in a condenser rig similar to that useiin the old Method 3030 for used or dirty oilsMethods 3010 and 3020 can be used for volatilsolvents if the solvent is first carefully evaporatedthe volume replaced with water, before completinithe procedure.

ICP=Inducitivey Coupled Plasma Emission Spectroscopy.

GFAA=Graphite Furnace Atomic Absorption.FLAA=Flame Atomic Absorption.Source: EPA 1986.

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TABLE A-2.-ANALYSIS METHODS

Sample Sampling procedure Constituent Analysis method

Flue Gas .......................................................... EPA Method 5 ................................................ Particulates ....................................................Multiple Metals Train ..................................... Total Metals .................................................... See Methods Listed Below.

Antimony .......................................................... 7041EPA Method 108 .................. Arsenic ............................................................. 7060,b 7061 .b

Barium .........................6 010, 7080.EPA Method 104 .................. Beryllium ....................... 6010, 7090, 7091.

Cadmium ....................... 6010, 7130, 7131.Chromium(rotal) ............................................. 6010, 7190, 7191.Chromtum(VI) .................................................. 7195-7198.1Lead ................................................................. 6010, 7420, 7421.

EPA Method 101A ................. Mercury ............................ ! ............................... 7470,b 7471.9Silver .......................... 6010, 7760.cThallium ........ ............... 6010 7841.

Other ASamples ............................................. Co mposite ...................................................... Antimony.......................................................... 7040.Arsenic ............................................................. 7060,b 7061.bBarium ....................................................... 6010,7080.Beryllium ........................................... ....-... 6010 '7090, 7091.Cadmium ..................... .. 6010,7130,7131.Chromium(Total) ............................................ 6010, 7190. 7191.Chmmlum(VI) .. ......................................... 7195-7198.,Lead ................................................................ 6010, 7420, 7421.Mercury.............................. 7470,b 7471.'Silver ...... ........... ............................ 6010, 7760.'Thallium ........... i ............................................ 6010, 7841.

These chromium (VI) methods are for aqueous matrices only. EPA has nearly completed validation of a stack sampling methodology for hexavalent chromium.See Knoll J.E., US EPA, and Carver, A.C., Entropy Environmentalists, Inc., "Sampling and Analytical Methodology for Measurement of Low Levels of HexavalentChromium from Stationary Sources". Paper presented at EPA/AWMA Symposium at Raleigh, N.C., May 1989, as revised by draft dated November 10, 1989, entitled"Method Cr-Determination of Hexavalent Chromium Emissions from Stationary Sources".

b This method Includes digestion for aqueous matrices (no digestion method from Table 111-12 Is necessary.'This method include digestion for all matrices (no digestion method from Table 111-12 is necessary).4 Includes waste feed, bottom ash and scrubber liquor.

The Multiple Metals Methodidentified in Table A-2 is a method EPAis proposing to determine emissions ofthe 10 metals that would be regulated bythe proposed rule: antimony, arsenic,barium, beryllium, cadmium, chromium,lead, mercury, silver, and thallium. Theproposed method is described in U.S.EPA, "Proposed Methods for StackEmissions Measurement of CO, 02,THC, HCL, and Metals at HazardousWaste Incinerators, Vol. VI of theHazardous Waste IncinerationGuidance Series", November 1989. Themethod uses a Method 5 train (40 CFRPart 60, Appendix A) modified toinclude the following impingers:

(1) empty (used for condensatecollection; may be omitted for a drysource];

(2) 5 percent HNO3 and 10 percentH20 2;.

(3) same as 2;(4) 4 percent KMnO 4 and 10 percent

H2SO 4;(5) same as 4; and(6) silica gel (to protect pump and

meter).The document also provides alternate

methods and conditions under whichonly a single metal analysis can beperformed.

A-2: Hydrogen ChlorideMeasurement Methods

Methods of sampling and analysis ofthe waste feed for chloride and stackgas for HCI are described in detail inEPA Publication No. SW-846, withadditional information provided in theOSW Methods Manual. The latterdocument discusses the acceptablemethods of sampling and analysis ofstack gases for hydrogen chloride.Briefly, the sampling may be performedusing one of several trains. The EPAMethod 5 train (40 CFR part 60,appendix A), or the semivolatile trainbased on Method 0010 of EPAPublication No. SW-846, may be usedby incorporating a collection solution inthe second and third impingers. Thestack gas may also be sampled using aspecific HCI train incorporating thesame solution impingers.

Analysis of the gas sample may beperformed using Method 9251Colorimetric Automated Ferricyanide or9252 Titimetric Mercuric Nitrate asdescribed in Volume IC, Chapter 5 ofEPA Publication No. SW-846, or the IonChromatography Method 300.0 asdescribed in "Method for ChemicalAnalysis of Water and Waste," EPAPublication No. EPA600/4-79-020 (NTISNo. PB84-128677). Specialconsiderations including interferences,cost, reliability, etc., that should beconsidered in selecting the method to be

used are described in the ProposedMethods Manual.

For the reasons set forth in thepreamble, it is proposed to amend title40 of the Code of Federal Regulations asfollows:

PART 260-HAZARDOUS WASTEMANAGEMENT SYSTEM: GENERAL

I. In part 260:1. The authority citation for part 260

continues to read as follows:Authority: 42 U.S.C. 6905, 6912(a), 6921

Through 6927, 6930 6934, 6935, 6937, 6938,6939, and 6974.

2. In § 260.10, it is proposed to revisethe definition of "incinerator" and theintroductorytext of "industrial furnace".and add in alphabetical order,definitions for "carbon regenerationunit," "infrared incinerator", and"plasma arc incinerator" to read asfollows:

§ 260.10 Definitions.* * * * *

Carbon regeneration unit means anyenclosed thermal treatment device usedto regenerate spent activated carbon.

Incinerator means any encloseddevice that:

(1) Uses controlled flame combustionand neither meets the criteria forclassification as a boiler or carbon

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regeneration unit, nor is listed as anindustrial furnace; or

(2) Meets the definition of infraredincinerator or plasma arc incinerator.

Industrial furnace means any of thefollowing enclosed devices that areintegral components of manufacturingprocesses and that use thermaltreatment to accomplish recovery ofmaterials or energy:* * *

Infrared incinerator means -anyenclosed device that uses electricpowered resistance heaters as a sourceof radiant heat and which is not listedas an industrial furnace.-:

Plasma arc incinerator means anyenclosed device using a high intensityelectrical discharge or arc as a source ofheat and which is not listed as anindustrial furnace.

3. It is proposed to amend paragraph(a) of § 260.11 by adding the followingreference in alphabetical order:

§ 260.11 References.(a) * * *"Risk Assessment Guideline for

Permitting Hazardous Waste ThermalTreatment Devices (RAG)."* * * * *

PART 261-IDENTIFICATION ANDLISTING OF HAZARDOUS WASTE

I. In part 261:1. The authority citation for part 261

continues to read as follows:

Authority: 42 U.S.C. 6905, 6912(a), 6921,6922, and 6937.

2. It is proposed to amend § 261.2 byredesignating paragraph (d)(2) as (d)[3)and adding a new paragraph (d)(2).

§ 261.2 Definition of solid waste.

(d) * * *(2) Secondary materials fed to a

halogen acid furnace that are identifiedor exhibit a characteristic of ahazardous waste as defined in subpartsC or D of this part.

PART 264-STANDARDS FOROWNERS AND OPERATORS OFHAZARDOUS WASTE TREATMENT,STORAGE, AND DISPOSALFACILIES

III. In part 264:1. The authority citation for part 264

continues to read as follows:

Authority: 42 U.S.C. 6905, 6912(a), 6924, and6925.

2. It is proposed to amend § 264.342 by

revising paragraphs (a) and (b)(1) toread as follows:

§ 264.342 Principal organic hazardousconstituents (POHCs).

(a) All organic hazardous constituentsin the waste feed must be treated to theextent required by the performancestandards of § 264.343(a).

(b) (1) Principal organic hazardousconstituents (POHCs) are thosecompounds for which compliance withparagraph (a) of this section shall bedemonstrated in a trial burn. One ormore POHCs shall be designated by theAdministrator for each waste feed in thetrial burn. POHCs shall be designatedbased on the degree of difficulty ofincineration of the organic constituentsin the waste and on their concentrationor mass in the waste feed consideringthe results of waste analyses submittedwith part B of the permit application.POHCs are most likely to be selectedfrom among those compounds listed inpart 261, Appendix VIII of this chapterthat are also present in the normalwaste feed. However, if the applicantdemonstrates to the RegionalAdministrator's satisfaction that acompound not listed in Appendix VIII ornot present in the normal waste feed is asuitable indicator of compliance withparagraph (a) of this section, thatcompound may be designated as aPOHC. Such POHCs need not be toxicor organic compounds.

3. It is proposed to amend § 264.343 byrevising paragraph (c), redesignatingparagraph (d) as (g) and revising thenewly redesignated paragraph (g), andadding new paragraphs (d), (e), (f), and(h) to read as follows:

§ 264.343 Performance standards.

(c) An incinerator burning hazardouswaste must not emit particulate matterin excess of 180 milligrams per drystandard cubic meter (0.08 grains perdry standard cubic feet) when correctedfor the amount of oxygen in the stackgas according to the formula:

14P.=P. X

E-Y

Where P, is the correctedconcentration of particulate matter, Pmis the measured concentration ofparticulate matter, E is the percentage ofoxygen contained in the air used forcombustion, and Y is the measuredconcentration of oxygen in the stackgas, using the Orsat method for oxygen

analysis of dry flue gas, presented inpart 60, appendix A (Method 3), of thisChapter. This correction factor is to beused by all hazardous wasteincinerators. For incinerators usingambient air for combustion, the value ofE will be 21, while for incinerators usingoxygen enriched air for combustion, thevalue of E will be greater than 21.

(d) Carbon monoxide (1)(i) Tier I:Except as provided by paragraph(d)(1)(ii) of this section, an incineratorburning hazardous waste must beoperated so that carbon monoxide (CO)levels (corrected to 7% oxygen, drybasis) in the stack gas do not exceed 100ppmv on an hourly rolling average basis.

(ii) Tier II: A hazardous wasteincinerator may be operated at COlevels higher than those provided byparagraph (d)(1)(i) of this sectionprovided the owner or operatordemonstrates that emissions of totalhydrocarbons (THC) at that higher COlevel do not pose an unacceptablehealth risk to the maximum exposedindividual. For the purpose of thisdemonstration, THC must be monitoredcontinuously during the trial burn inaccordance with methods specified in"Test Methods for Evaluating SolidWaste, Physical/Chemical Methods,"EPA publication SW-846 asincorporated by reference in § 260.11.For purposes of this subpart, THC willbe considered to pose acceptable healthrisk when:

(A) The maximum hourly averageTHC emissions rate during the trial burndoes not exceed the THC ScreeningLimits identified in the "RiskAssessment Guideline for PermittingHazardous Waste Thermal TreatmentDevices" (RAG) as incorporated byreference in § 260.11; or

(B) When the owner or operatordemonstrates by site-specific dispersionmodeling that THC emissions will notresult in an increased lifetime cancerrisk to the maximum exposed individualof more than 10 - 5 using proceduresprescribed in the RAG (incorporated byreference in § 260.11).

(2) CO limits will be established in thepermit using one of the followingformats:

(i) Hourly rolling average format,where the permitted CO level is 100ppmv for Tier I and the average of theCO levels occurring during the trial burnfor Tier II; or

(ii) Cumulative hourly time abovelimit format, where two CO limits willbe specified-one which cannot beexceeded at any time and the otherwhich can be exceeded only for a

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specified time in any clock hour. TheseCO limits, and time of exceedance inany hour, shall be established to ensurethat the total permitted CO emissions donot exceed those that would be allowedunder the hourly rolling average formatin any hour of operation.

(3) Correction factor for oxygen. (i)When the oxygen content in the stackgas differs from 7 percent, measured COlevels must be corrected for the actualamount of oxygen in the stack gasaccording to the formula:

14CO¢= CO. X

E-Y

where CO, is the correctedconcentration of CO in the stack gas,COrn is the measured CO concentrationmeasured in accordance with "TestMethods For Evaluating Solid WastePhysical/Chemical Methods," EPAPublication SW-846 as incorporated byreference in § 260.11, E is the percentageof oxygen contained in the air used forcombustion, and Y is the measuredoxygen concentration in the stack gasusing the Orsat method of oxygenanalysis in part 60, Appendix A (Method3) of this Chapter if oxygen is not-monitored continuously, or using themethod prescribed in "Test Methods forEvaluating Solid Waste Physical/Chemical Methods," EPA PublicationSW-846 is incorporated by reference in§ 260.11, when oxygen is monitoredcontinuously. This correction procedureis to be used by all hazardous wasteincinerators. For incinerators usingambient air for combustion, the valuefor E will be 21. For incinerators usingoxygen-enriched air, the value for E willbe greater than 21,

(ii) For purposes of compliance withthe hourly rolling average format ofparagraph (d)(2)(i) of this section, thestack gas oxygen level, correction factor,and the corrected CO value shall bedetermined continuously. Forcompliance with the cumulative timeabove limit format of paragraph (d](2)(ii)of this section, the appropriate stackoxygen level and the CO correctionfactor shall initially be determinedduring the trial burn (or by data in lieuof a trial burn) and, at a minimum,annually thereafter. The RegionalAdministrator may specify in the permitmore frequent determinations ifnecessary to ensure that the correctionfactor is- accurate. That correction factorshall be applied continuously to providecorrected CO values continuously.

(4) The CO limits provided by thissection are based on dry stack gas.When instruments that measure CO on

a wet basis are used, a correction factorshall be used to convert the measuredvalue to a dry basis. This correction"factor shall initially be determinedduring the trial burn and annuallythereafter unless otherwise specified Inthe permit.

(e) Metals. (1)'The owner andoperator must comply with the metalscontrols provided by paragraphs (e)(2),(e)(3), or (e)(4)of this section.

(2) Feed Rate Screening Limits. (i) Forthe carcinogenic metals arsenic,cadmium, chromium, and beryllium, thesum of the ratios of the actual feed ratein lbs/hr to the Feed Rate ScreeningLimit for all the metals shall not exceed1.0, as determined by the followingequation:

n Actual Feed Rate,

X Feed Rate Screening Limit 4

where:n=number of carcinogenic metalsActual Feed Ratei=the actual feed rate for

metal "i", in lb/hr.Feed Rate Screening Limit, the limit

provided in the RAG for metal "i", in lb/hr.

The Screening Limits are specified in theRAG, incorporated by reference in§ 260.11, for the applicable effectivestack height, terrain type and urban orrural land use classification.

(ii) For each of the noncarcinogenicmetals antimony, barium, lead, mercury,silver, and thallium, the actual feed ratein lb/hr shall not exceed the Feed RateScreening Limits specified in the RAG(incorporated by reference in § 260.11)for the applicable effective stack height,terrain type, and urban or rural land useclassification.

(3) Emissions Screening Limits. (i) Forthe carcinogenic metals arsenic,cadmium, chromium, and beryllium, thesum of the ratios of the actual emissionrate to the Emissions Screening Limit forall the metals shall not exceed 1.0, asdetermined by the following equation:where:

n =number of carcinogensPredicted Ambient Concentration = the

maximum off-site annual average groundlevel concentration for metal "i", in ug/ins, at the 10- 5 risk level.

Total chromium emission ratesmeasured in accordance with "TestMethods for Evaluating Solid Waste;Physical/Chemical Methods," EPAPublication SW-846, as incorporated byreference In § 260.11 are to be used forthis determination, unless theapplicant's sampling and analysisprocedures are capable of reliablydetermining hexavalent chromium

emission rates to the satisfaction of theAdministrator.

(ii) For each of the noncarcinogenicmetals, antimony, barium, lead, mercury,silver, and thallium, the predictedmaximum annual average off-siteground level concentration shall notexceed the Reference AirConcentrations provided by the RAG.

(iii) Conformance with therequirements provided by thisparagraph is demonstrated by stackemissions .testing in accordance with theMultiple Metals Method in "TestMethods for Evaluating Solid Waste;Physical/Chemical Methods," EPAPublication SW-846, as incorporated byreference in § 260.11 and 40 CFR 60Reference Methods 1-5. and dispersionmodeling in accordance with EPA's"Guideline on Air Quality Models(Revised)" (see § 270.6).

(5) For facilities with more than onestack handling emissions from theburning of hazardous waste in anincinerator, boiler, or industrial furnace,aggregate emissions from all such stackswill be considered In demonstratingcompliance with paragraph (d) of thissection according to proceduresprescribed in the RAG.

(f) Hydrogen chloride. (1) The ownerand operator must comply with the totalchlorine or hydrogen chloride (HCI)controls provided by paragraphs (f)(2),(f)(3), or (f)(4) of this section.

(2) Feed Rate Screening Limits. Theactual feed rate of total chlorine in lb/hrshall not exceed the Feed RateScreening Limits provided in the RAG(see § 260.11) for the applicable effectivestack height and terrain type, as definedin the RAG.

n Actual Feed Rate1

X" Emissions Screening Limit,i=1

where:n = number of carcinogenic metalsActual Emission Rate, = the emission rate

measured during the trail bum orprovided in lieu of the trail burn formetal "i", in g/s.

Emissions Screening Limit, = the limitprovided in the RAG for metal "i", in g/s.

The Screening Limits are specified in theRAG (incorporated by reference in§ 260.11) for the applicable effectivestack height, terain type and urban orrural land use classification. Totalchromium emission rates measured inaccordance with "Test Methods forEvaluating Solid Waste; Physical/Chemical Methods," EPA PublicationSW-846, as incorporated by reference in

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§ 260.11 are to be used for thisdetermination unless the applicant'semissions sampling and analysisprocedures are capable of reliablydetermining hexavalent chromiumemissions rates to the satisfaction of theAdministrator, and

(ii) For each of the carcinogenicmetals antimony, barium, lead, mercury,silver, and thallium, the actual emission:rate shall not exceed the EmissionsScreening Limits provided in the RAG(incorporated by reference in § 260.11)for the applicable effective stack height,*terrain type, and urban versus rural landuse classification.

(iii) Metals emissions must bemeasured in accordance with theMultiple Metals Method in "TestMethods for Evaluating Solid Waste;Physical/Chemical Methods," EPAPublication SW-846, as incorporated byreference in §260.11 and 40 CFR 60Reference Methods 1-5.

(4) Site-specific risk analysis. (I) Forthe carcinogenic metals arsenic,cadmium, chromium and beryllium, thesum of the ratios of the predictedmaximum off-site annual averageground level concentration to the Risk-Specific Dose for all carcinogenic metalsshall not exceed 1.0, as determined bythe following equation.

n Predicted AmbientConcentration, 1.0

Risk Specific Dose,

(3) Emissions Screening Limits. Theemission rate of HCI in g/s shall notexceed the Emissions Screening Limitsprovided in the RAG for the applicableeffective stack height and terrain type.

(4) Site specific risk analysis. HCIemissions shall not result In anexceedance of the 3-minute exposureReference Air Concentration (RAC) orthe annual exposure RAC provided bythe RAG. Conformance with thisstandard shall be demonstrated asprovided by paragraphs (e)(4) (iii) and(iv) of this section.

(5) For facilities with more than onestack handling emissions from theburning of hazardous waste in anincinerator, boiler, or industrial furnace,aggregate emissions from all such stackswill be considered in demonstratingcompliance with paragraph (e) of thissection according to proceduresprescribed in the RAG.

(g) For purposes of permitenforcement, compliance with theoperating requirements specified in thepermit (under § 264.345) will be regardedas compliance with this section.However, evidence that compliance

with those permit conditions isinsufficient to ensure compliance withthe performance requirements of thissection may be "information" justifyingmodification, revocation, or reissuanceof a permit under § 270.41 of thischapter.

(h) The Feed Rate and EmissionScreening Limits for metals and HCIprovided by paragraphs (e) and (f) ofthis section, and the Emission ScreeningLimits for THC provided by paragraph "(d) of this section may not be protectivein the following situations:

(1) Facility is located in a narrow'valley less than 1 km wide; or

(2) Facility has a stack taller than 20mand is located such that the terrain risesto the physical stack height within 1 kmof the facility; or

(3) Facility has a stack taller than 20mand is located within 5 km of theshoreline of a large body of water (suchas an ocean or large lake); or

(4) The facility property line is within200m of the stack and the physical stackheight is less than 10m; or

(5) On-site receptors are of concern,and the physical stack height is lessthan 10m.For these cases, and for any otherreasons deemed appropriate, theRegional Administrator may, at hisdiscretion, require the owner/operatorto submit a site-specific air qualitydispersion analysis consistent with"Guideline on Air Quality Models(Revised)," EPA Publication 450/2-78-027R as incorporated by reference in§ 270.6 of this chapter. Where such ananalysis is required, the determinationof source limits shall be in accordancewith the procedures employed forestablishing the limits specified by thissection.

4. It is proposed to amend § 264.345 byrevising paragraph (a) and adding textto the end of paragraph (e) to read asfollows:

§ 264.345 Operating requirements.

(a) An incinerator must be operated inaccordance with operating requirementsspecified in the permit whenever there ishazardous waste in the incinerator.These will be specified on a case-by-case basis as those demonstrated (in atrial burn or in alternative data asspecified in § 264.344(b) and includedwith part B of the facility's permitapplication) to be sufficient to complywith the performance standards of§ 264.343.

(e) * * * When the hazardous wastefeed is cut off, the temperature in the(secondary) combustion chamber must

be maintained and emission controlequipment must continue to function asspecified in the permit until all residualsolids exit the combustion chamber. Forcases when waste feed cutoff occurredbecause of exceeding the CO limits, thewaste feed may be resumed only afterthe CO levels are brought down topermitted levels.* * * *

5. It is proposed to revise the headingof § 264.347 and amend it by revisingparagraphs (a) and (c); revising andredesignating paragraph (d) as (e); andadding new paragraph (d) to read asfollows:§ 264.347 Monitoring, inspections, andreporting requirements.

(a) The owner or operator mustconduct, as a minimum, the followingmonitoring while incinerating hazardouswaste:

(1) Combustion temperature and theindicators of combustion gas velocity,air pollution control device parameters,and other parameters as specified in thefacility permit as necessary to ensurethe performance standards of § 24.343are met, must be continuously monitoredby equipment that records theparameters at least every 30 seconds.

(2) CO must be monitored andrecorded on a continuous basis inaccordance with SW-846 (asincorporated in § 260.11) at a point inthe incinerator downstream of thecombustion zone and prior to release tothe atmosphere.

(3) As a part of the permit renewalprocess or upon request by the RegionalAdministrator, sampling and analysis ofthe waste and exhaust emissions mustbe conducted to verify that the operatingrequirements established in the permitachieve the performance standards of§ 264.343.

(c) The automatic waste cutoff systemand associated alarms must be tested atleast weekly to verify operability, unlessthe applicant demonstrates to theRegional Administrator that weeklyinspections will unduly restrict or upsetoperations and that less frequentinspection will be adequate. At aminimum, operational testing must beconducted monthly.

(d) The continuous monitors requiredunder § 264.347(a) must be calibrated atleast weekly, unless the applicantdemonstrates to the RegionalAdministrator that weekly calibrationswill unduly restrict or upset operationsand that less frequent calibration will beadequate. At a minimum, they must becalibrated monthly.

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(e) The monitoring and inspectiondata must be recorded and the recordsmust be placed in the operating logrequired by § 264.73. The operator mustrecord in the operating log whenever thehazardous waste feed is cut off inaccordance with § 264:345(e). The recordmust include date, time andcircumstances of each cut offand theaction the operator took to address theproblem. Quarterly reports of automaticwaste feed cutoffs, the circumstances ofthe cutoffs, and any noncomplianceincidents must be submitted to theAdministrator within 30 days of the endof the applicable reporting quarter.

PART 270-EPA ADMINISTEREDPERMIT PROGRAMS: THEHAZARDOUS WASTE PERMITPROGRAM

IV. In part 270:1. The authority for part 270 continues

to read as follows:Authority: 42 U.S.C. 6905. 6912, 6924, 0925.

6927, 6939 and 6974.

2. It is proposed to amend § 270.6 (a)by adding a new reference inalphabetical order to read as follows:

§ 270.6 References.(a) * * *"Guideline on Air Quality Models

(Revised]," EPA Publication Number 45012-78-027R (OAQPS Guideline No. 1.2-080),available from National TechnicalInformation Service, Springfield, Virginia,Order No. PB 86-245286.

3. It is proposed to amend § 270.19 byrevising paragraph (a) introductory test,and paragraphs (c)[1)(iii), (c)[3), (c)(6)(ii).and (c)(7), by removing paragraph(c)(6)(vii) and redesignating paragraphs(c)(6) (viii) and (ix) as (c)[6) (vii) and(viii), respectively, and by addingparagraphs (c)(9), (e) and (f) to read asfollows:

§ 270.19 Specific Part 8 Informationrequirements for Incinerators.a * * * *

(a) When seeking an exemption under§ 264.340 (b) or (c) of this chapter(ignitable, corrosive, or reactive wastesonly), the applicant must perform andsubmit an analysis of representativesamples of all waste streams for whichthe applicant is seeking an exemption,for all the part 261, appendix VIIIconstituents which would reasonably beexpected to be in the waste. Theconstituents excluded from analysismust be identified, and documentationprovided to support that they would notreasonably be expectedto be in the

waste. The applicant must also submit,as appropriate:

( c) • •(c1)(iii An identification of any

hazardous metal's and hazardousorganic constituents, listed in part 261,appendix VIii, of this chapter, and totalchlorine which are present in the wasteto be burned, except that the applicantneed not analyze for constituents listedin part 261, appendix VIII, of thischapter which would reasonably not beexpected to be found in the waste. Theconstituents excluded from analysismust be identified and the basis for theirexclusion stated. The waste analysismust rely on analytic techniquesspecified in "Test Methods forEvaluating Solid Waste, Physical/Chemical Methods," (EPA PublicationSW-846 as incorporated by reference in§ 260.11 and referenced in 40 CFR part261, appendix III), or their equivalent.

.(3) A description and analysis of thewaste to be burned shall be comparedwith the waste for which data fromoperations or trial burns are provided tosupport the contention that a trial burnis not needed. The data should includethe items listed in paragraph (c)(1) ofthis section. This analysis shouldspecify the POHCs, metals, and totalchlorine which the applicant hasidentified in the waste for which apermit is sought, and any differencestherefrom for the waste for which thetrial burn data are provided.

(6) • .(ii) Total waste feed rate, individual

metal feed rates (specified separatelyfor liquid (pumpable) wastes, solidwastes, and organometals), and totalchlorine feed rate.a a a a a

(7) Such supplemental information asthe Director finds necessary to achievethe purposes of this paragraph. Thisinformation includes, but is notnecessarily limited to:

(i) Physical stack height.(i) Stack flue gas temperature.(iii) Topographical data up to a.

distance of 5 km around the stack, andland use data within a 3 km radius ofthe stack, including maps and aerialphotographs.

(iv) Stack gas flow rate.

(9) Information that the Director findsnecessary to demonstrate compliancewith the Feed Rate Screening Limits,Emissions Screening Limits, or Site-Specific Risk Analysis standards formetals and HCI at levels which do not

pose an unacceptable risk to humanhealth and the environment and whichmay include the following data:

(i) For Emissions Screening Limits andSite-Specific Risk Analysis, metals andFICI emission rates from the stack forthe facility whose data is proposed to beused in lieu of the trial burn.

(ii) For Site-Specific Risk Analysis,predictions of maximum annual averageoff-site ground level concentrations fon-site concentrations must be consideredif individuals reside on site) for metalsand HCI for the facility seeking thepermit, as well as:

(A) Meteorological data;(B) Rationale for air dispersion model

selection;(C) Topographic considerations.(iii) A comparison of the actual

emission rates from the facility whosedata is being proposed to the expectedemission rates of the facility seeking thepermit.* a a a

(e) Applicants seeking to be permittedfor burning of wastes containing metalsor chlorine must sibmit information ordocumentation needed for the Directorto determine whether the incinerator issituated in complex or noncomplexterrain, whether the incinerator islocated in an urban or rural land usearea as defined in the RAG, and anyother information necessary to set theappropriate metals at HCI permitconditions. The applicant must set forththe methodology and all informationused for the determination.

(f) Applicants seeking to be permittedunder the Site-Specific Risk Analysisprovisions of § 264.343 for THC, metalsand total chlorine must submit adispersion modeling plan with part B ofthe permit application. The Director willreview the plan for conformance withthe "Guideline on Air Quality Models(Revised)" (incorporated by reference,see § 270.6). The Director will eitherapprove the modeling plan or determinethat an alternate or supplementary planis appropriate. After completion of thetrial burn to measure metals, THC and-ICI emission rates, the owner or

operator must conduct dispersionmodeling according to the approvedplan and submit the results to theDirector in the trial burn report. TheDirector will determine whether theresults are in conformance with therequirements of § 264.343 (d), (e), and If)of this chapter and will establishappropriate operating requirements asrequired by § 264.345 of this chapter.

5. It is proposed to amend § 270.62 byrevising paragraphs (b)(2)(i)(C),

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(b){2}{i){D), {b}{2)[ii)[F), {b){2){ii)[C},(b}{2){vii}, (b)(4), {b}{6}{i}, {b}{6}{ii},{b}{6}{iii}, {b}{6}{v}, {b}{6}{viii}, {b){6){ix},

(b)(8), (c) introductory text, and (c)(1);by adding new paragraphs (b)(2)(i)(E),and (b)(2)(ii)(K), and redesignatingparagraph (b)(10) as (b)(11) and revisingit and adding a new paragraph (b)(10) toread as follows:

§ 270.62 Hazardous waste Incineratorpermits.* * * * *

(b) ***(2) * * *(iJ * * *

(C) An identification of any hazardousmetals, hazardous organic constituentslisted in part 261, appendix VIII of thischapter, and total chlorine, which arepresent in the waste to be burned,except that the applicant need notanalyze for constituents listed in part261, appendix VIII, of this chapter whichwould not reasonably be expected to befound in the waste or are easier todestroy than the most difficult POHC tobe tested in the trial burn. Theconstituents excluded from analysismust be identified, and the basis for theexclusion stated. The waste analysismust rely on analytical techniquesspecified in "Test Methods forEvaluating of Solid Waste, Physical/Chemical Methods," EPA PublicationSW-846 as incorporated by reference, in§ 260.11 or their equivalent.

(D) An approximate quantification ofthe hazardous constituents includingmetals and total chlorine identified inthe waste, within the precision producedby the analytical methods specified in"Test Methods for Evaluating SolidWaste, Physical/Chemical Methods,"EPA Publication SW-846 asincorporated by reference, in § 260.11, ortheir equivalent.

(E) Total chlorine concentration of thewaste in the form and composition inwhich it will be burned.

(ii) * * *(F) Description of automatic waste

feed cut-off system(s), and how they areconnected to any thermal relief valve orbypass system.

(G) Stack gas monitoring, pollutioncontrol equipment, and heights of allstacks or combustion gas dischargevents, measured from ground level.* * * * *

(K) Location and description of anybypass systems, and any backup orredundant equipment to limit thenumber of bypass events.* * * * *

(vii) Procedures for rapidly stoppingwaste feed, shutting down theincinerator, maintaining temperature inthe combustion chamber until all waste

exit the incinerator, and controllingemissions in the event of an equipmentmalfunction or activation of any thermalrelief valve or other bypass systemincluding calculations demonstratingthat emissions will be controlled duringsuch an event (sufficient oxygen forcombustion and maintaining negativepressure), and the procedures forexecuting the "contingency plan"whenever a relief valve is used, thuscausing an emergency release ofemissions.* * * * *

(4) Based on the waste analysis datain the trial burn plan, the Director willspecify as trial Principal OrganicHazardous Constituents (POHCs), thoseconstituents for which destruction andremoval efficiencies must be calculatedduring the trial burn.

(i) These trial POHCs will be specifiedby the Director based on his estimate ofthe difficulty of incineration of theconstituents identified in the wasteanalysis, their concentration or mass inthe waste feed, and, for wastes listed inpart 261, subpart D, of this chapter, thehazardous waste organic constituent orconstituents identified in appendix VIIof that part as the basis for listing.

(ii) The use of a POHC surrogate asproved by § 264.342(b)(1) of this chaptermay be appropriate in certaincircumstances based on the Director'sestimate of the difficulty of chemicalanalysis of the waste, the lowconcentrations of POHCs in the waste,the low stability of waste POHCs in thewaste, or other appropriate factors. Suchsurrogates need not be organic, toxic orpresent in the waste. The Director mayapprove the use of a POHC surrogateprovided it is suitable based on theperformance standard of § 264.343(a),the composition of the wastes to beincinerated, and the sampling andanalysis requirements.* * * * *

(6) * * *(i) A quantitative analysis of thd trial

POHCs, total chlorine, and metals in thewaste feed to the incinerator.

(ii) A quantitative analysis of theexhaust gas for the concentration andmass emissions of the trial POHCs(POHC surrogates), oxygen (02), and, asappropriate, metals and hydrogenchloride.

(iii) A quantitative analysis of thescrubber water (if any), ash residues,and other residues, for the purpose ofestimating the fate of the trial POHCs,HCI, and metals, as appropriate.

(v) A computation of the total chlorinefeed rate and, if applicable, the HCI

emission rate, in accordance with'§ 264.343(f) of this chapter.* * * * *

(viii) A continous measurement oftemperature, combustion gas velocity,and all waste feed rates.

(ix) A continuous measurement in theexhaust gas of carbon monoxide (CO)and oxygen (02) (as required), and THCemissions if complying with 40 CFR264.343(d)(1)(ii) in lieu of 40 CFR264.343(d)(1)(i).* * * * *

(8) All data collected during any trialburn, and subsequent analyses of alltrial burn samples including assuranceand control (QA/QC) data must besubmitted to the Director within 90 daysof completion of the trial burn.* * * * *

(10) All trial burn runs for whichpermit conditions will be establishedmust be passed (i.e., conformance mustbe demonstrated for all performancestandards provided by § 246.343 of thischapter for all runs). A minimum ofthree runs must be passed for each setof permit conditions. One of the threeruns may be disregarded if the Directorbelieves there is sufficient reason.

(11) Based on the results of the trialburns, the Director shall set theoperating requirements in the finalpermit according to § 264.345 of thischapter. The permit modification shallproceed as a minor modificationaccording to § 270.42.

(c) For the purposes of allowingoperation of a new hazadous wasteincinerator following completion of thetrial burn and prior to final modificationof the permit conditions to reflect thetrial burn results, the Director mayestablish permit conditions, includingbut not limited to allowable waste feeds,emission rates, and operating conditionssufficient to meet the requirements of§ 264.345 of this chapter, in the permit toa new hazardous waste incinerator.These permit conditions will be effectivefor the minimum time required tocomplete sample analysis, datacomputation, and submission of the trialburn results by the applicant, andmodification of the facility permit by theDirector.

(1) Applicants must submit astatement with the permit application,which identifies the conditionsnecessary to operate in compliance withthe performance standards of § 264.343of this chapter, during this period. Thisstatement should include, at a minimum,restrictions on waste constituents, wastefeed rates, emission rates, and operatingparameters in § 264.345 of this chapter.[FR Doc. 90-8821 Filed 4-1-90; 8:45 am]BILLING CODE 6560-50-M

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