FRN, September 30, 1999: Final Standards for … statement that you will obtain paired ... cement kiln industry express concern ... install a new, clean filter,

52927Federal Register / Vol. 64, No. 189 / Thursday, September 30, 1999 / Rules and Regulations

209 RSD, or ‘‘relative standard deviation’’, is adimensionless number greater than zero defined asthe standard deviation of the samples, divided bythe mean of the samples. In the special case whereonly 2 data represent the sample, the mathematicsof determining the relative standard deviationsimplifies greatly to |CA¥CB |/(CA + CB), where CA

and CB are the concentration results from the twotrains that represent the pair.

210 See Chapter 11, Section 2 of the technicalbackground document for details on the statisticalprocedures used to derive these benchmarks:USEPA, ‘‘Final Technical Support Document forHazardous Waste Combustor MACT Standards,Volume IV: Compliance With the Hazardous WasteCombustor Standards,’’ July 1999.

used to increase method precision. Thisrequirement applies whether you useMethod 5i to demonstration compliancewith the emission standard or tocorrelate a particulate matter CEMS. Inaddition, if you elect to petition theAdministrator for approval to use aparticulate matter CEMS and elect touse Method 5 to correlate the CEMS,you must also obtain paired Method 5data to improve method precision and,thus, the correlation.

During our CEMS testing, wecollected particulate matter data usingtwo simultaneously-conducted manualmethod sampling trains. We called theresults from these simultaneous runs‘‘paired data.’’ We discussed the use ofpaired trains in the December 1997NODA as being optional but requestedcomment on whether we should requirepaired trains, state a strong preferencefor them, or be silent on the issue. Manycommenters believe paired trainsshould be used at all times so precisioncan be documented. With thesecomments in mind, and consistent withour continued focus on the collection ofhigh quality emission measurements,we include a requirement in Method 5ito obtain paired data. Method 5i alsoincludes a minimum acceptable relativestandard deviation between these datapairs. As discussed below, both data inthe pair are rejected if the data exceedthe acceptable relative standarddeviation.

To improve the correlation betweenthe manual method and a particulatematter CEMS, we also recommend thatsources electing to use Method 5 alsoobtain paired Method 5 data. Again,data sets that exceed an acceptablerelative standard deviation, as discussedbelow, should be rejected. Thisrecommendation will be implementedduring the Administrator’s review ofyour petition requesting use aparticulate matter CEMS. If you elect tocorrelate the CEMS using Method 5, youare expected to include in your petitiona statement that you will obtain paireddata and will conform with ourrecommended relative standarddeviation for the paired data.

iii. What Are the Procedures forIdentifying Outliers? We haveestablished maximum relative standarddeviation values for paired data for bothMethod 5i and Method 5. If a data pairexceed the relative standard deviation,the pair is identified as an outlier andis not considered in the correlation of aparticulate matter CEMS with thereference method. In addition, Method5i pairs that exceed the relative standarddeviation are considered outliers andcannot be used to document compliancewith the emission standard.

In the initial phase of our CEMS tests,we established a procedure foreliminating imprecise data. Thisconsisted of eliminating a set of paireddata if the data disagree by more thansome previously established amount.Two identical methods running at thesame time should yield the same result;if they do not, the precision of both datais suspect. Commenters agree with theneed to identify and eliminate imprecisedata to enhance method precision. Thisis an especially important step whencomparing manual particulate mattermeasurements to particulate matterCEMS measurements. As a result, weinclude criteria in Method 5i to ensuredata precision.

When evaluating the particulatematter CEMS Demonstration Test data,we screened the data to remove theseprecision outliers. Data outliers at thattime were defined as paired data pointswith a relative standard deviation 209 ofgreater than 30 percent. We developedthis 30% criterion by analyzinghistorical Method 5 data. Severalcommenters, including a particulatematter CEMS vendor with extensiveEuropean experience with correlationprograms, recommend that we tightenthe relative standard deviation criteria.We concur, because Method 5i is moreprecise than Method 5 given theimprovements discussed above.Therefore, one would logically expect areasonable precision criterion such asthe relative standard deviation derivedfrom Method 5i data to be less than asimilarly reasonable one derived fromMethod 5 data. We investigated theparticulate matter CEMS DemonstrationTest data base as well other availableMethod 5i data (such as the data froma test program recently conducted atanother US incinerator). We concludethat a 10% relative standard deviationfor particulate matter emissions greaterthan or equal to 10 mg/dscm, increasedlinearly to 25% for concentrations downto 1 mg/dscm, is a better representationof acceptable, precise Method 5i paireddata 210. Data obtained at concentrations

lower than 1 mg/dscm have no relativestandard deviation limit.

The relative standard deviationcriterion for Method 5 data used forparticulate matter CEMS correlationscontinues to be 30%.

iv. Why Didn’t EPA Issue Method 5ias Guidance Rather than Promulgating Itas a Method? Most commenters statethat Method 5i should be guidancerather than a published method and itshould not be a requirement forperforming particulate matter CEMScorrelation testing or documentingcompliance with the emission standard.In particular, several commenters in thecement kiln industry express concernover the limitations of Method 5iregarding the mass of particulate itcould collect. This section addressesthese concerns.

We have promulgated Method 5i as amethod because it provides significantimprovement in precision and accuracyof low level particulate mattermeasurements relative to Method 5.Consequently, although Method 5i isnot a required method, we expect thatpermitting officials will disapprovecomprehensive performance test plansthat recommend using Method 5 for lowlevel particulate levels. Further, weexpect that petitions to use a particulatematter CEMS that recommendperformance acceptance criteria (e.g.,confidence level, tolerance level,correlation coefficient) based oncorrelating the CEMS with Method 5measurements will be disapproved. Thisis because we expect the CEMS to beable to achieve better acceptance criteriavalues using Method 5i (because it ismore accurate and precise than Method5), and expect better relative standarddeviation between test pairs (resultingin lower cost of correlation testingbecause fewer data would be screenedout as outliers).

Given that we expect and wantwidespread use of Method 5i, and toensure that its key provisions arefollowed, it is appropriate to promulgateit as a method rather than guidance. Ifthe procedure were issued only asguidance, the source or stack testercould choose to omit key provisions,thus negating the benefits of themethod.

Relative to the direct reference inMethod 5i that the method is ‘‘mosteffective for total particulate mattercatches of 50 mg or less,’’ this means themethod is most effective at hazardouswaste combustors with particulatematter emissions below approximately45 mg/dscm (∼0.02 gr/dscf). Thisapplicability statement is not intendedto be a bright line; total train catchesexceeding 50 mg would not invalidate

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52928 Federal Register / Vol. 64, No. 189 / Thursday, September 30, 1999 / Rules and Regulations

211 Stack testers have developed ways to deal withplugging of a filter. Many stack testers simplyremove the filter before it plugs, install a new, cleanfilter, and continue the sampling process wherethey left off with the old filter. The mass gain isthen the total mass accumulated on all filters duringthe run. However, using multiple filters for a singlerun takes more time, not only to install the newfilter but also to condition and weigh multiplefilters for a single run. For Method 5i, it would alsoinvolve more capital cost because the stack testerwould need more light-weight filter assemblies toperform the same number of runs. For these reasonsand even though the situation can be acceptablymanaged, it is impractical to have the filter plug.This led to our recommendation that Method 5i isbest suited for particulate matter (i.e., filter)loadings of at most 50 mg, or stack concentrationsof less than 45 mg/dscm (roughly 0.02 gr/dscf).

212 See USEPA, ‘‘Final Technical SupportDocument for Hazardous Waste Combustor MACTStandards, Volume IV: Compliance With theHazardous Waste Combustor Standards,’’ July 1999.

the method. Rather, we include thisguidance to users of the method to helpthem determine whether the method isapplicable for their source. Note thatthis statement is found in theapplicability section of the method,rather than the method descriptionsections that follow. As such, thereference is clearly an advisorystatement, not a quality assurancecriterion. Total train catches above 50mg are acceptable with the method andthe results from such trains can be usedto document compliance with theemission standard and for correlatingCEMS. But, users of Method 5i areadvised that problems (such as pluggingof the filter) may arise when emissionsare expected to exceed 45 mg/dscm. 211

v. What Additional Costs AreAssociated with Method 5i?Commenters raise several issuesregarding the additional costs ofperforming Method 5i testing relative tousing Method 5. There is an added costfor the purchase of new Method 5i filterhousings. These new lightweightholders are the key addition to theprocedure needed to improve precisionand accuracy and represent a one-timeexpense that emission testing firms orsources that perform testing in-housewill have to incur to perform Method 5i.We do not view this cost as significantand conclude that the use of a light-weight filter housing is a reasonable andappropriate feature of the method.

Other commenters suggest that therequirement for pesticide-grade acetonein the version of Method 5i contained inthe December 1997 NODAunnecessarily raises the cost ofperforming the method. Instead, theyask us to identify a performance levelfor the acetone instead of a graderequirement because it would allow testcrews to meet that performance in themost economical manner. We agree thatprescribing a certain type of acetonemay unnecessarily increase costs andremoved the requirement for pesticide-grade acetone. Accordingly, the same

purity requirements cited in Method 5for acetone are maintained for Method5i. The prescreening of acetone purity inthe laboratory prior to field use,consistent with present Method 5requirements, is also maintained inMethod 5i.

Commenters make similar cost-relatedcomments relative to the requirementfor Teflon beakers. At the request ofseveral commenters, we have expandedthe requirement for Teflon beakers toallow the use of beakers made fromother similar light-weight materials.Because materials other than Teflon

can be used to fabricate light-weightbreakers, changing the requirement froma technology basis to a performancebasis will reduce costs while achievingthe performance goals of the method.

There were no significant commentsregarding the added cost of paired-traintesting.

vi. What Is the PracticalQuantification Limit of the Method 5iFilter Sample? We received severalcomments related to the minimumdetection limit of Method 5i, including:the minimum sample required,guidance on how long to sample, whatmass should ideally be collected on anyfilter, and the practical quantificationlimit.

Commenters are concerned that whilewe address the maximum amount ofparticulate matter the method couldhandle, we are silent on the issue ofwhat minimum sample is required. Thisis important because analytical errors,such as weighing of the filters, tend tohave the same error value associatedwith it irrespective of the mass loading.To address this concern, Method 5iprovides guidance on determining theminimum mass of the collected samplebased on estimated particulate matterconcentrations.

Related to the particulate masscollection issue is the issue of how longa user of Method 5i needs to sample inorder to an adequate amount ofparticulate on the filter. The amount ofparticulate matter collected is directlyrelated to time duration of the samplingperiod, i.e., the longer one samples, themore particulate is collected and vice-versa. Therefore, Method 5i providesguidance on selecting a suitablesampling time based on the estimatedconcentration of the gas stream.

Both these issues directly relate tohow much particulate matter shouldideally be collected on any individualfilter. Our experience indicates aminimum target mass is 10 to 20 mg.

Finally, we conclude that the targetedpractical quantification limit for Method5i is 3.0 mg of sample. Discussion ofhow this quantification limit is

determined is highly technical andbeyond the scope of this preamble. Seethe technical support document formore details.212

vii. How Are Blanks Used withMethod 5i? Several commentersquestion the use of acetone blanks ormade recommendations for additionalblanks. We clarify in this section thecollection and use of sample blank data.

We recognize that high blank resultscan adversely effect the analyticalresults, especially at low particulatematter concentrations. To avoid theeffect high blank results can have on theanalytical results, today’s Method 5iadopts a strategy similar to several ofthe organic compound test procedures(such as Method 23 in part 60 andMethod 0010 in SW–846) that requirecollection of blanks but do not permitcorrection to the analytical results.Collection and analysis of blanksremains an important component in thesampling and analysis process fordocumenting the quality of the data,however. If a test run has high blankresults, the data may be suspect.Permitting officials will address thisissue on a case-by-case basis.

The importance of minimizingcontamination is stressed throughoutMethod 5i for both sample handling anduse of high purity sample media. Ifproper handling procedures areobserved, we expect that the blankvalues will be less than the methoddetection limit or within the value forconstant weight determination (0.5 mg).Therefore, the allowance for blankcorrection that is provided in Method 5is not permitted in Method 5i. Themethod also recommends severaladditional types of blanks to providefurther documentation of the integrityand purity of the acetone throughout theduration of the field sampling program.

b. What Is the Status of ParticulateMatter CEMS Performance Specification11 and Quality Assurance/QualityControl Procedure 2? We are notfinalizing proposed PerformanceSpecification 11 and Quality Assurance/Quality Control Procedure 2 because thefinal rule does not require the use ofparticulate matter CEMS. We consideredstakeholder comments on thesedocuments, however, and haveincorporated many comments into thecurrent drafts. We plan to publish thesedocuments when we address theparticulate matter CEMS requirement. Inthe interim, we will make themavailable as guidance to sources that are



213 One exception is the destruction and removalefficiency standard, for which compliance is basedon a single test run and not the average of threeruns.

214 The two days assumes sources will conduct atotal of 18 runs, 6 runs in each of the low, medium,and high particulate matter emission ranges. Toapprove use of a particulate matter CEMS, we willlikely require that a minimum of 15 runs comprisea correlation test. If this is the case, some runs willlikely be eliminated because they fail method orsource-specific quality assurance/quality controlprocedures.

considering the option of using aparticulate matter CEMS to documentcompliance.

c. How Have We Resolved OtherParticulate Matter CEMS Issues? In thissection we discuss two additionalissues: (1) Why didn’t we requirecontinuous opacity monitors forcompliance with the particulate matterstandard for incinerators andlightweight aggregate kilns; and (2) canhigh correlation emissions testing runsexceed the particulate matter standard?

i. Why Didn’t We Require ContinuousOpacity Monitors for ComplianceAssurance for Incinerators andLightweight Aggregate Kilns? Asdiscussed elsewhere in today’s notice,we require cement kilns to usecontinuous opacity monitors (COMS) tocomply with a 20 percent opacitystandard to ensure compliance with theparticulate matter emission standard.This is the opacity component of theNew Source Performance Standard forparticulate matter for Portland cementplants. See § 60.62. Because we areadopting the mass-based portion of theNew Source Performance Standard forparticulate matter as the MACTstandard (i.e., 0.15 kg/Mg dry feed), theopacity component of the New SourcePerformance Standard is useful forcompliance assurance.

We do not require that incineratorsand lightweight aggregate kilns useopacity monitors for complianceassurance because we are not able toidentify an opacity level that isachievable by sources using MACTcontrol and that would ensurecompliance with the particulate matterstandards for these source categories.This is the same issue discussed abovein the context of particulate matterCEMS and is the primary reason that weare not requiring use of these CEMS atthis time.

Although we are requiring thatcement kilns use COMS for complianceassurance, these monitors cannotprovide the same level of complianceassurance as particulate matter CEMS.Opacity monitors measure acharacteristic of particulate matter (i.e.,opacity) and cannot correlate with themanual stack method as well as aparticulate matter CEMS. COMS areparticularly problematic for sourceswith small stack diameters (e.g.,incinerators) and low emissions becauseboth of these factors contribute to verylow opacity readings which results inhigh measurement error as a percentageof the opacity value. Thus, we areobtaining additional data to supportrulemaking in the near future to requireuse of particulate matter CEMS forcompliance assurance.

Approximately 80 percent ofhazardous waste burning cement kilnsare not currently subject to the NewSource Performance Standard and manyof these sources may not be equippedwith COMS that meet PerformanceSpecification 1 in appendix B, part 60.Thus, many hazardous waste burningcement kilns will be required to installCOMS, even though we intend torequire use of particulate matter CEMSin the near future. We do not believethat this requirement will be overlyburdensome, however, because sourcesmay request approval to installparticulate matter CEMS rather thanCOMS. See § 63.8(f). Our testing ofparticulate matter CEMS at a cementkiln will be completed well beforesources need to make decisions on howbest to comply with the COMSrequirement of the rule. We willdevelop regulations and guidance onperformance specifications andcorrelation criteria for particulate matterCEMS as a result of that testing, andsources can use that guidance to requestapproval to use a particulate matterCEMS in lieu of a COMS. We expectthat most sources will elect to use thisapproach to minimize compliance costsover the long term.

ii. Can High Correlation Runs Exceedthe Particulate Matter Standard? Thefinal rule states that the particulatematter and opacity standards of parts60, 61, 63, 264, 265, and 266 (i.e., allapplicable parts of Title 40) do notapply during particulate matter CEMScorrelation testing, provided that youcomply with certain provisionsdiscussed below that ensure that theprovision is not abused. This provision,as the rest of the rule, is effectiveimmediately. Thus, you need not waitfor the compliance date to takeadvantage of this particulate matterCEMS correlation test provision.

We include this provision in the rulebecause many commenters questionwhether high correlation test runs thatexceed the particulate matter emissionstandard constitute noncompliance withthe standard. We have responded to thisconcern previously by stating that asingle manual method test run thatexceeds the standard does not constitutenoncompliance with the standardbecause compliance is based on theaverage of a minimum of three runs.213

We now acknowledge, however, thatduring high run correlation testing asource may need to exceed the emissionstandard even after averaging emissions

across runs. Similarly, a source mayneed to exceed a particulate matteroperating parameter limit. Given thebenefits of compliance assurance usinga CEMS, we agree with commenters thatshort-term excursions of the particulatematter standard or operating parameterlimits for the purpose of CEMScorrelation testing is warranted. Thebenefits that a CEMS provides forcompliance assurance outweighs theshort-term emissions exceedances thatmay occur during high end emissionscorrelation testing. Consequently, wehave included a conditional waiver ofthe applicability of all Federalparticulate matter and opacity standards(and associated operating parameterlimits).

The waiver of applicability of theparticulate matter and opacity emissionstandards and associated operatingparameter limits is conditioned on thefollowing requirements to ensure thatthe waiver is not abused. Based oninformation from commenters andexpertise gained during our testing, therule requires that you develop andsubmit to permitting officials aparticulate matter CEMS correlation testplan along with a statement of whenand how any excess emissions willoccur during the correlation tests (i.e.,how you will modify operatingconditions to ensure a wide range ofparticulate emissions, and thus a validcorrelation test). If the permittingofficials fail to respond to the test planin 30 days, you can proceed with thetests as described in the test plan. If thepermitting officials comment on theplan, you must address those commentsand resubmit the plan for approval.

In addition, runs that exceed anyparticulate matter or opacity emissionstandard or operating parameter limitare limited to no more than a total of 96hours per correlation test (i.e., includingall runs of all test conditions). Wedetermined that the 96 hour totalduration for exceedances for acorrelation test is reasonable because itis comprised of one day to increaseemissions to the desired level and reachsystem equilibrium, two days oftesting 214 at the equilibrium conditionfollowed by a return to normalequipment settings indicative ofcompliance with emissions standardsand operating parameter limits, and one



day to reach equilibrium at normalconditions. Finally, to ensure theseperiods of high emissions are due to thebona fide need described here, a manualmethod test crew must be on-site andmaking measurements (or in the eventsome unforseen problem develops,prepared to make measurements) atleast 24 hours after you make equipmentor workplace modifications to increaseparticulate matter emissions to levels ofthe high correlation runs.

3. What Is the Status of Total MercuryCEMS?

We are not requiring use of totalmercury CEMS in this rulemakingbecause data in hand do not adequatelydemonstrate nationally that these CEMSare reliable compliance assurance toolsat all types of facilities. Nonetheless, weare committed to the development ofCEMS that measure total mercuryemissions and are continuing to pursuethe development of these CEMS in ourresearch efforts.

In the April 1996 NPRM, we proposedthat total mercury CEMS be used forcompliance with the mercury standards.We also said if you elect to use amultimetals CEMS that passed proposedacceptability criteria, you could use thatCEMS instead of a total mercury CEMSto document compliance with themercury standard. Finally, we indicatedthat if neither mercury nor multimetalCEMS were required in the final rule(i.e., because they have not beenadequately demonstrated), complianceassurance would be based on specifiedoperating parameter limits.

In the March 1997 NODA, we elicitedcomment on early aspects of ourapproach to demonstrate total mercuryCEMS. And, in the December 1997NODA, we presented a summary of thedemonstration test results and ourpreliminary conclusion that we wereunable to adequately demonstrate totalmercury CEMS at a cement kiln, a sitejudged to be a reasonable worst-case forperformance of the total mercury CEMS.As new data are not available, wecontinue to adhere to this conclusion,and comments received in response tothe December 1997 NODA concur withthis conclusion. Therefore, we are notrequiring total mercury CEMS in thisrulemaking.

Nonetheless, the current lack of datato demonstrate total mercury CEMS at acement kiln or otherwise on a genericbases (i.e., for all sources within acategory) does not mean that thetechnology, as currently developed,cannot be shown to work at particularsources. Consequently, the final ruleprovides you the option of using totalmercury CEMS in lieu of complying

with the operating parameter limits of§ 63.1209(l). As for particulate matterand other CEMS, the rule allows you topetition the Administrator (i.e.,permitting officials) under § 63.8(f) touse a total mercury CEMS based ondocumentation that it can meetacceptable performance specifications,correlation acceptance criteria (i.e.,correlation coefficient, tolerance level,and confidence level). Although we arenot promulgating the proposedperformance specification for totalmercury CEMS (PerformanceSpecification 12) given that we were notable to document that a mercury CEMScan meet the specification in a (worst-case) cement kiln application, theproposed specification may be useful toyou as a point of departure for aperformance specification that you mayrecommend is achievable andreasonable.

4. What Is the Status of the ProposedPerformance Specifications forMultimetal, Hydrochloric Acid, andChlorine Gas CEMS?

We are not promulgating proposedPerformance Specifications 10, 13, and14 for multimetal, hydrochloric acid,and chlorine gas CEMS because we havenot determined that the CEMS canachieve the specifications.

In the April 1996 NPRM, we proposedperformance specifications formultimetal, hydrochloric acid, andchlorine gas CEMS to allow sources touse these CEMS for compliance with themetals and hydrochloric acid/chlorinegas standards. Given that we have notdemonstrated that these CEMS can meettheir performance specifications and ourexperience with a mercury CEMS wherewe were not able to demonstrate that themercury CEMS could meet ourproposed performance specification, weare not certain that these CEMS canmeet the proposed performancespecifications. Accordingly, it would beinappropriate to promulgate them.

As discussed previously, weencourage sources to investigate the useof CEMS and to petition permittingofficials under § 63.8(f) to obtainapproval to use them. The proposedperformance specifications may beuseful to you as a point of departure inyour efforts to document performancespecifications that are achievable andthat ensure reasonable correlation withreference manual methods.

5. How Have We Addressed OtherIssues: Continuous Samplers as CEMS,Averaging Periods for CEMS, andIncentives for Using CEMS?

a. Are Continuous Samplers a CEMS?Several commenters, mostly owner/

operators of on-site incinerators, suggestthat we should adjust certain CEMScriteria (e.g., averaging period, responsetime) to allow use of a continuoussampler known as the 3M Method. The3M Method is a continuous metalssampling system. It automaticallyextracts stack gas and accumulates asample on a filter medium over anydesired period—24 hours, days, orweeks. The sample is manuallyextracted, analyzed, and reported.Various incinerator operators are usingor have expressed an interest in usingthis type of approach to demonstratecompliance with current RCRA metalsemission limits. Many commenterscontend that the 3M Method is a CEMSand that we developed our performancespecifications for CEMS to excludetechniques like the 3M Method.

After careful analysis, we concludethat the 3M Method is not a CEMS. Itdoes not meet our long-standingdefinition of a CEMS in parts 60 or 63.Specifically, it is not a fully automatedpiece(s) of equipment used to extract asample, condition and analyze thesample, and report the results of theanalysis in the units of the standard.Also, the 3M Method is unable to‘‘complete a minimum of one cycle ofoperation (sampling, analyzing, anddata recording) for each successive 15-minute period’’ as required by§ 63.8(c)(4)(ii). As a result, making thesubtle changes (e.g., to the averagingperiod, response time) to our multimetalCEMS performance specification thatcommenters recommend would not alterthe fact that the device does notautomatically analyze the sample on thefrequency required for a CEMS.

A continuous sampler (coupled withperiodic analysis of the sample) isinferior to a CEMS for two reasons.First, if the sampling period is longerthan the time it takes to perform threemanual performance tests, compliancewith the standard cannot be assured.Approaches like the 3M Method tend tohave reporting periods on the order ofdays, weeks, or even a month. Thereporting period is comprised of thetime required to accumulate the sampleand the additional time to analyze thesample and report results. Because thestringency of a standard is a function ofboth the numerical value of the standardand the averaging period (e.g., at a givennumerical limit, the longer theaveraging period the less stringent thestandard), a compliance approachhaving a sampling period greater thanthe 12 hours we estimate it may take toconduct three manual method stack testruns using Method 29 cannot ensure



215 A technical support document for the February1991 municipal waste combustor rule contains agood description of how not only the numericallimit, but the averaging period as well, determinesthe overall stringency of the standard. SeeAppendices A and B found in ‘‘Municipal WasteCombustion: Background Information forPromulgated Standards and Guidelines—Summaryof Public Comments and Responses Appendices Ato C’’, EPA–450/3–91–004, December 1990.

216 Actually, the CEMS averaging period can be nolonger than the time required to conduct three runsof the performance test to ensure compliance withthe standard. Although compliance with thestandard would be ensured if the CEMS averagingperiod were less than the time required to conductthe performance test, this approach would be overlystringent because it would ensure compliance withan emission level lower than the standard.

compliance with the standard.215 If thesampling period were greater than thetime required to conduct three test runs,the numerical value of the standardwould have to be reduced to ensure anequally stringent standard.Unfortunately, we do not know how toderive alternative emission limits as afunction of the averaging period thatwould be equivalent to the emissionstandard. We raised this issue atproposal, and commenters did not offera solution.

Second, the results from a continuoussampler are reported after the fact,resulting in higher excess emissionsthan with a CEMS. Depending on thesample analysis frequency, it could takedays or weeks to determine that anexceedance has occurred and thatcorrective measures need to be taken. ACEMS can provide near real-timeinformation on emissions such thatexceedances can be avoided orminimized.

Absent the generic availability ofmultimetal CEMS, continuous samplerssuch as the 3M Method may nonethelessbe a valuable compliance tool. We haveacknowledged that relying on operatingparameter limits may be an imperfectapproach for compliance assurance.Sampling and analysis of feedstreams todetermine metals feedrates can beproblematic given the complexities ofsome waste matrices. In addition, theoperating parameters for the particulatematter control device for which limitsmust be established may not alwayscorrelate well with the device’s controlefficiency for metals and thus metalsemissions. Because of these concerns,we encourage sources to investigate thefeasibility of multimetal CEMS. But,absent a CEMS, a continuous samplermay provide an attractive alternative orcomplement to some of the operatingparameter limits under §§ 63.1209 (l)and (n). You may petition permittingofficials under § 63.8(f) to use the 3MMethod (or other sampler) as analternative method of compliance withthe emissions standards. Permittingofficials will balance the benefits of acontinuous sampler with the benefits ofthe operating parameter limits on a case-by-case basis.

b. What Are the Averaging Periods forCEMS and How Are They Implemented?We discuss the following issues in this

section: (1) Duration of the averagingperiod; (2) frequency of updating theaveraging period; and (3) how averagingperiods are calculated initially andunder intermittent operations.

i. What Is the Duration of theAveraging Period? We conclude that asix-hour averaging period is mostappropriate for particulate matterCEMS, and a 12-hour averaging periodis most appropriate for total mercury,multi metals, hydrogen chloride, andchlorine gas CEMS.

We proposed that the averagingperiod for CEMS (i.e., other than carbonmonoxide, hydrocarbon, and oxygen) beequivalent to the time required toconduct three runs of thecomprehensive performance test usingmanual stack methods. As discussedabove and at proposal, we proposed thisapproach because, to ensure compliancewith the standard, the CEMS averagingperiod must be the same as the timerequired to conduct the performancetest.216

Commenters suggest two generalapproaches to establish averagingperiods for CEMS: technology-based andrisk-based. Commenters supporting atechnology-based approach favor ourproposed approach and rationale wherethe time duration of three emissionstests would be the averaging period forCEMS. Commenters favoring a risk-based approach state that the averagingperiod should be years rather than hoursbecause the risk posed by emissions atlevels of the standard were not found tobe substantial, assuming years ofexposure. We disagree with thisrationale. CEMS are an option (thatsources may request under § 63.8(f)) todocument compliance with theemission standard. As discussed above,if the averaging period for CEMS werelonger than the duration of thecomprehensive performance test, wecould not ensure that a source maintainscompliance with the standards.

Establishing an averaging periodbased on the time to conduct threemanual method stack test runs issomewhat subjective. There is no fixedsampling time for manual methods—sampling periods vary depending on theamount of time required to ‘‘catch’’enough sample. Thus, we have somediscretion in selecting an averagingperiod using this approach. Commenters

generally favor longer averaging periodsas an incentive for using CEMS (i.e.,because a limit is less stringent ifcompliance is based on a long versusshort averaging period). We agree thatchoosing a longer averaging periodwould provide an incentive for the useof CEMS, but conclude that the selectedaveraging period must be within therange (i.e., high end) of times requiredto perform the three stack test runs.

We derive the averaging period forparticulate matter CEMS as follows.Most particulate matter manual methodtests are one hour in duration, but a fewstack sampling companies sample forlonger periods, up to two hours.Therefore, we use the high end of therange of values, 2 hours, as the basis forcalculating the averaging period. Werecommend a six-hour rolling averageconsidering that it may require 2 hoursto conduct each of three stack tests.

For mercury, multi-metals,hydrochloric acid, and chlorine gasCEMS, we recommend a 12-hour rollingaveraging. The data base we used todetermine the standards shows that thesampling periods for manual methodtests for these standards ranged fromone to four hours. Choosing the highend of the range of values, 4 hours, asthe basis for calculating the averagingperiod, we conclude that a 12-hourrolling average would be appropriate.

ii. How Frequently Is the RollingAverage Updated? We conclude that therolling average for particulate matter,total mercury, and multimetal CEMSshould be updated hourly, while therolling average for hydrochloric acidand chlorine gas CEMS should beupdated each minute.

We proposed that all rolling averageswould be updated every minute andwould be based on the average of theone-minute block average CEMSobservations that occurred over theaveraging period. This proposed one-minute update is the same that is usedfor carbon monoxide and totalhydrocarbon CEMS under the RCRA BIFregulations. (We are retaining thatupdate frequency in the final rule forthose monitors, and recommend it forhydrochloric acid and chlorine gasCEMS.)

Commenters favor selecting thefrequency of updating the rollingaverage taking into account thevariability of the CEMS and limitationsconcerning how the correlation data arecollected. We agree with this approach,as discussed below.

1. Particulate Matter CEMS.Commenters said that particulate matterCEMS correlation tests areapproximately one hour in durationand, if the rolling average were updated



217 Data availability is defined as the fraction,expressed as a percentage, of the number of block-hours the CEMS is operational and obtaining validdata during facility operations, divided by thenumber of block-hours the facility was operating.

each minute, the CEMS would observemore variability in emissions withinthis one hour than the manual method(which is an average of those emissionsduring the hour). For this reason, weconclude it is reasonable that particulatematter CEMS data be recorded as ablock-hour and that the rolling averagebe updated every hour as the average ofthe previous six block-hours. Updatingthe particulate matter CEMS every houralso means the number of complianceopportunities is the same irrespective ofwhether a light-scattering or beta-gageparticulate matter CEMS is used (i.e.,because beta-gage CEMS makeobservations periodically while light-scattering CEMS make observationscontinuously).

Furthermore, to ensure consistencywith existing air rules governing CEMSother than opacity, a valid hour shouldbe comprised of four or more equallyspaced measurements during the hour.See § 60.13(h). This means that batchsystems, such as beta gages, mustcomplete one cycle of operation every15 minutes, or more frequently ifpossible. See § 63.8(c)(4)(ii). CEMS thatproduce a continuous stream of data,such as light-scattering CEMS, willproduce data throughout the hour.

You may not be able to have fourvalid 15-minute measurement in anhour, however, to calculate an hourlyblock-average. Examples include whenthe source shuts down or the CEMSproduces flagged (i.e., problematic) data.In addressing this issue, we balancedthe need for the average of themeasurements taken during the hour tobe representative of emissions duringthe hour with the need to accommodateproblems with data availability that willdevelop. We conclude that a particulatematter CEMS needs to sample stack gasand produce a valid result from thissample for most of the hour. This meansthat the CEMS needs to be observingstack gas at least half (30 minutes, ortwo 15-minute cycles of operation) ofthe block-hour. Emissions from lessthan one hour might beunrepresentative of emissions duringthe hour, and on balance we concludethat this approach is reasonable. If aparticulate matter CEMS does notsample stack gas and produce a validresult from that sample for at least 30minutes of a given hour, the hour is nota valid block-hour. In documentingcompliance with the data availabilityrecommendation in the draftperformance specification, invalidblock-hours due to unavailability of theCEMS that occur when the source is inoperation count against dataavailability. If the hour is not validbecause the source was not operating for

more than 30 minutes of the hour,however, the invalid block-hour doesnot count against the data availabilityrecommendation.217

2. Total Mercury and MultimetalCEMS. As discussed for particulatematter CEMS, we also expect manualmethods will be required to correlatetotal mercury and multimetal CEMSprior to using them for compliance. Forthe reasons discussed above in thecontext of particulate matter CEMS, wetherefore recommend the observationsfrom these CEMS be recorded as block-hour averages and that the 12-hourrolling average be updated every hourbased on the average of the previous 12block-hour averages.

3. Hydrochloric Acid and ChlorineGas CEMS. Unlike the particulatematter, total mercury, and multimetalCEMS, hydrochloric acid and chlorinegas CEMS are likely to be calibratedusing Protocol 1 gas bottles rather thancorrelated to manual method stack testresults. Therefore, the variability ofobservations measured by the CEMSover some averaging period versus theduration of a stack test is not an issue.We conclude that it is appropriate toupdate the 12-hour rolling average forthese CEMS every minute, as requiredfor carbon monoxide and hydrocarbonsCEMS.

iii. How Are Averaging PeriodsCalculated Initially and underIntermittent Operations?

1. Practical Effective Date of RollingAverages for CEMS. As discussed inPart Five, Sections VII.B.4 above in thecontext of continuous monitoringsystems in general, CEMS recordingswill not become effective forcompliance monitoring on thecompliance date until you haverecorded enough observations tocalculate the rolling average applicableto the CEMS. For example, the sixhourly rolling average for particulatematter CEMS does not become effectiveuntil you have recorded six block-hoursof observations on the compliance date.Given that compliance with thestandards begins nominally at 12:01 amon the compliance date, the six hourrolling average for particulate matterCEMS does not become effective as apractical matter until 6:01 am on thecompliance date. Similarly, the 12-hourrolling average for a multimetal CEMSdoes not become effective until youhave recorded 12 block-hours ofobservations after the compliance date.Thus, the 12-hour rolling average for

multimetals CEMS becomes effective asa practical matter at 12:01 p.m. on thecompliance date.

We adopt this approach simplybecause a rolling average does not existuntil enough observations have beenrecorded to calculate the rolling average.

2. How Rolling Averages AreCalculated Upon IntermittentOperations. We have determined thatyou are to ignore periods of time whenCEMS observations are not recorded forany reason (e.g., source shutdown)when calculating rolling averages. Forexample, consider how the six hourrolling average for a particulate matterCEMS would be calculated if a sourceshuts down for yearly maintenance fora three week period. The first one-hourblock average value recorded when thesource renews operations is added tothe last 5 one-hour block averagesrecorded before the source shut downfor maintenance to calculate the sixhour rolling average.

We adopt this approach for allcontinuous monitoring systems,including CEMS, because it is simpleand reasonable. See discussion in PartFive, Section B.4 above.

c. What Are the Incentives for UsingCEMS as Alternative Monitoring? Westrongly support the use of CEMS forcompliance with standards, even thoughwe are not requiring their use in today’srule (except for carbon monoxide,hydrocarbon, and oxygen CEMS) for thereasons discussed above. We endorsethe principle that, as technologyadvances, current rules should not actas an obstacle to adopting new CEMStechnologies for compliance. Forinstance, today’s rule does not requiretotal mercury CEMS becauseimplementation and demonstrationobstacles observed during our testsunder what we consider worst-caseconditions (i.e., a cement kiln) could notbe resolved in sufficient time to requiretotal mercury CEMS at all hazardouswaste combustors. However, we fullyexpect total mercury CEMS willimprove to the point that the technicalissues encountered in our tests can beresolved. At that point, we do not wantthe compliance regime of today’s rule—comprised of emissions testing andlimits on operating parameters—to be sorigid as to preclude the use of CEMS.Commenters are generally supportive ofthis concept, but note that facilitieswould be reluctant to adopt newtechnologies without adequateincentives. This section describespotential incentives: emissions testingwould not be required; limits onoperating parameters would not applywhile the CEMS is in service; and thefeedstream analysis requirements for the



218 By ‘‘optional use of CEMS’’, we mean usingCEM not required by this rule, i.e., other than thosefor carbon monoxide, oxygen, and hydrocarbon.

219 You are not restricted to those specified in§ 63.1209. You may identify parameters for yoursource that correlate better with particulateemissions than those we have specified generically.

parameters measured by the CEMS (i.e.,metals or chlorine) would not apply.

i. What Incentives Do CommentersSuggest? Several commenters suggestthat we provide various incentives toencourage development andimplementation of new and emergingCEMS. Comments by the Coalition forResponsible Waste Incineration (CRWI)include a variety of actions to encouragevoluntary installation of CEMS,218

including: Reduce testing for anyparameter measured by a CEMS to thecorrelation and maintenance of thatCEMS; waive operating parameter limitsthat are linked to the pollutantmeasured by the CEMS; minimizeregulatory oversight on waste analysis ifcompliance is consistentlydemonstrated by a CEMS; increase theemission limit for a source using aCEMS to account for the uncertainty ofCEMS observations; allow a phase-inperiod when a source can evaluateCEMS performance and developmaintenance practices and the CEMSwould not be used for compliance;allow a phase-in period to establish areasonable availability requirement forthat CEMS at a particular location; andallow sources to evaluate CEMS on atrial basis to determine if theseinstruments are appropriate for theiroperations with no penalties if the unitsdo not work or have excessivedowntime. Many of CRWI’s suggestionshave merit, as discussed below.

ii. How Do We Respond toCommenter’s Recommended Incentives?

1. Waiver of Emissions Testing andOperating Parameter Limits. CRWI’sfirst two suggestions (reduced testingand waiver of operating parameterlimits) are closely linked. The purposeof conducting a comprehensiveperformance test is to documentcompliance with emission standardinitially (and periodically thereafter)and establish limits on specifiedoperating parameters to ensure thatcompliance is maintained. Because aCEMS ensures compliancecontinuously, it serves the purpose ofboth the performance test andcompliance with operating parameterlimits. Accordingly, we agree withCRWI that both emissions testing andoperating parameter limits for thepollutant in question would not applyto sources using a CEMS.

There is one key caveat to thisposition, however. Because 100%availability of any CEMS is unrealistic,we require a means of assuringcompliance with the emission standards

during periods when the CEMS is notavailable. To meet that need, you mayelect to install redundant CEMS orassure continuous compliance bymonitoring and recording traditionaloperating parameter limits duringperiods when the CEMS is not available.Most likely, you will elect to useoperating parameters as the back-upwhen the CEMS is unavailable becauseit would be a less expensive approach.You could establish these operatingparameter limits, though, through CEMSmeasurements rather thancomprehensive performance testmeasures. In fact, it may be prudent foryou to evaluate relationships betweenvarious operating parameters for theparticulate matter control device 219 andemission levels recorded by the CEMSto develop a good predictive model ofemissions. You could then petition theAdministrator (i.e., permitting officials)under § 63.8(f) to base complianceduring CEMS malfunctions on limits onalternative monitoring parametersderived from the predictive model.

2. Waiver of Feedstream AnalysisRequirements. If you obtain approval touse a CEMS for compliance under thepetitioning provisions of § 63.8(f), weagree with the commenter’srecommendation that you should not besubject to the feedstream analysisrequirements pertinent to the pollutantyou are measuring with a CEMS. Asexamples, if you use a total mercuryCEMS, you are not subject to a feedratelimit for mercury, and if you operate anincinerator and use a particulate matterCEMS, you are not subject to a feedratelimit for total ash.

If you are not subject to a feedratelimit for ash, metals, or chorine becauseyou use a CEMS for compliance, you arenot subject to the feedstream analysisrequirements for these materials. As apractical matter, however, this waivermay be moot because, as discussedabove, you will probably elect tocomply with operating parameter limitsduring CEMS malfunctions. However, asecond, back-up CEMS would also beacceptable. Absent a second CEMS, youwould need to establish feedrate limitsfor these materials as a back-upcompliance approach, and you wouldneed to know the feedrate at any timegiven that the CEMS may malfunction atany time. In addition, even when theCEMS is operating within theperformance specifications approved bythe permitting officials, you have theresponsibility to minimize exceedances

by, for example, characterizing yourfeedstreams adequately to enable you totake corrective measures if a CEMS-monitored emission is approaching thestandard. This level of feedstreamcharacterization, however, is less thanthe characterization required toestablish and comply with feedrateoperating limits during CEMSmalfunctions or absent a CEMS.

3. Increase the Averaging Period forCEMS-Monitored Pollutants. Theaveraging period for a CEMS-monitoredpollutant should not be artificiallyinflated (i.e., increased beyond the timerequired to conduct three manualmethod test runs) because the standardwould be less stringent. See previousdiscussions on this issue.

4. Increase Emission Limits toAccount for CEMS Uncertainty. We donot agree with the suggestion that anemission limit needs to be increased ona site-specific basis to accommodateCEMS inaccuracy and imprecision (i.e.,the acceptance criteria in the CEMSperformance specification that thesource recommends and the permittingofficials approve will necessarily allowsome inaccuracy and imprecision).Again, we encourage sources to use aCEMS because it is a better indicator ofcompliance than the promulgatedcompliance regime (i.e., periodicemissions testing and operatingparameter limits). We established thefinal emission standards withachievability (through the use of theprescribed compliance methods) inmind. We have accounted for theinaccuracies and imprecisions in theemissions data in the process ofestablishing the standard. See previousdiscussions in Part Four, Section V.D. Ifthe CEMS performance specificationacceptance criteria (that must beapproved by permitting officials under a§ 63.8(f) petition) were to allow theCEMS measurements to be moreinaccurate or imprecise than thepromulgated compliance regime ofperformance testing coupled with limitson operating parameters, the potentialfor improved compliance assurancewith the CEMS would be negated.Consequently, we reject the idea that thestandards need to be increased on a site-specific basis as an incentive for sourcesto use CEMS.

5. Allow a CEMS Phase-In Period.CRWI’s final three incentive suggestionsdeal with the need for a CEMS phase-in period. This phase-in period wouldbe used to evaluate CEMS performance,including identifying acceptableperformance specification levels,maintenance requirements, andmeasurement location. CRWI furthersuggested that the Agency not penalize



220 Other than carbon monoxide, hydrocarbon,and oxygen CEMS.

a source if the CEMS does not work orhas excessive downtime.

CRWI provided these comments inresponse to our proposal to requirecompliance using CEMS and thatsources document that the CEMS meetsa prescribed performance specificationand correlation acceptance criteria.Although we agree that a phase-inperiod would be appropriate, the issueis moot given that we are not requiringthe use of CEMS.220 Prior to submittinga petition under § 63.8(f) to gainapproval to use a CEMS, we presume asource will identify the performancespecification, correlation criteria, andavailability factors they believe areachievable. (We expect sources to usethe criteria we have proposed, asrevised after considering comments andfurther analysis and provided throughguidance, as a point of departure.) Thus,each source will have unlimited

opportunity to phase-in CEMS andsubsequently recommend under§ 63.8(f) performance specifications andcorrelation acceptance criteria.

We do not agree as a legal matter thatwe can state generically that CEMS dataobtained during the demonstrationperiod are shielded from enforcement ifthe CEMS data are credible and were toindicate exceedance of an emissionstandard. In this situation, we cannotshield a source from action by either bya regulatory agency or a citizen suit. Onbalance, given our legal constraints, ourpolicy desire to have CEMS used forcompliance, and uncertainty about theultimate accuracy of the CEMS data, wecan use our enforcement discretionwhether to use particulate matter CEMSdata as credible evidence in the eventthe CEMS indicates an exceedance untilthe time the CEMS is formally adoptedas a compliance tool. Sources andregulators may decide to draft a formaltesting agreement that states that theCEMS data obtained prior to the time

the CEMS is accepted as a compliancetool cannot be used as credible evidenceof exceedance of an emission standard.

D. What Are the Compliance MonitoringRequirements?

In this section we discuss theoperating parameter limits that ensurecompliance with each emissionstandard.

1. What Are the Operating ParameterLimits for Dioxin/Furan?

You must maintain compliance withthe dioxin/furan emission standard byestablishing and complying with limitson operating parameters. See§ 63.1209(k). The following tablesummarizes these operating parameterlimits. All sources must comply withthe operating parameter limitsapplicable to good combustionpractices. Other operating parameterlimits apply if you use the dioxin/furancontrol technique to which they apply.BILLING CODE 6560–50–P





BILLING CODE 6560–50–C



221 The temperature at the inlet to a cycloneseparator used as a prefiltering process for removinglarger particles is not limited. Cyclones do notsuspend collected particulate matter in the gasstream. Thus, these devices do not have the samepotential to enhance dioxin/furan formation aselectrostatic precipitators and fabric filters.

222 As discussed in Part Four, Section VIII,lightweight aggregate kilns can have extensiveducting between the kiln exit and the inlet to thefabric filter. If gas temperatures are limited at theinlet to the fabric filter, substantial dioxin/furanformation could occur in the ducting.

223 For this reason, you are not required todocument during the comprehensive performancetest that gas temperatures in the wet scrubber arenot greater than 400 °F. Also, we note that the 400°F temperature limit of the dioxin/furan standarddoes not apply to wet scrubbers, but rather to theinlet to a dry particulate matter control device andthe kiln exit of a lightweight aggregate kiln.

224 See USEPA, ‘‘Final Technical SupportDocument for Hazardous Waste Combustor MACTStandards, Volume IV: Compliance with theHazardous Waste Combustor Standards’’, February,1999.

Dioxin/furan emissions fromhazardous waste combustors areprimarily attributable to surface-catalyzed formation reactionsdownstream from the combustionchamber when gas temperatures are inthe 450 °F to 650 °F window (e.g., in anelectrostatic precipitator or fabric filter;in extensive ductwork between the exitof a lightweight aggregate kiln and theinlet to the fabric filter; as combustiongas passes through an incinerator wasteheat recovery boiler). In addition,dioxin/furan partition in two phases instack emissions: a portion is adsorbedonto particulate matter and a portion isemitted as a vapor (gas). Because ofthese factors, and absent a CEMS fordioxin/furan, we are requiring acombination of approaches to controldioxin/furan emissions: (1) Temperaturecontrol at the inlet to a dry particulatematter control device to limit dioxin/furan formation in the control device;(2) operation under good combustionconditions to minimize dioxin/furanprecursors and dioxin/furan formationduring combustion; and (3) compliancewith operating parameter limits ondioxin/furan emission controlequipment (e.g., carbon injection) thatyou may elect to use.

We discuss below the operatingparameter limits that apply to eachdioxin/furan control technique.

a. Combustion Gas TemperatureQuench. To minimize dioxin/furanformation in a dry particulate mattercontrol device that suspends collectedparticulate matter in the gas flow (e.g.,electrostatic precipitator, fabric filter),the rule limits the gas temperature at theinlet to these control devices 221 to levelsoccurring during the comprehensiveperformance test. For lightweightaggregate kilns, however, you mustmonitor the gas temperature at the kilnexit rather than at the inlet to theparticulate matter control device. This isbecause the dioxin/furan emissionstandard for lightweight aggregate kilnsspecifies rapid quench of combustiongas to 400 °F or less at the kiln exit. 222

If your combustor is equipped with awet scrubber as the initial particulatematter control device, you are notrequired to establish limits on

combustion gas temperature at thescrubber. This is because wet scrubbersdo not suspend collected particulatematter in the gas stream and gastemperatures are well below 400 °F inthe scrubber.223 Thus, scrubbers do notenhance surface-catalyzed formationreactions.

We proposed limits on the gastemperature at the inlet to a dryparticulate matter control device (see 61FR at 17424). Temperature control atthis location is important becausesurface-catalyzed formation reactionscan increase by a factor of 10 for every150 °F increase in temperature withinthe window of 350 °F to approximately700 °F. We received no adversecomments on the proposal, and thus, areadopting this compliance requirementin the final rule.

You must establish an hourly rollingaverage temperature limit based onoperations during the comprehensiveperformance test. The hourly rollingaverage limit is established as theaverage of the test run averages. See PartFive, Sections VII.B.1 and B.3 above fora discussion on the approach forcalculating limits from comprehensiveperformance test data.

b. Good Combustion Practices. Allhazardous waste combustors must usegood combustion practices to controldioxin/furan emissions by: (1)Destroying dioxin/furan that may bepresent in feedstreams; (2) minimizingformation of dioxin/furan duringcombustion; and (3) minimizing dioxin/furan precursor that could enhancepost-combustion formation reactions. Asproposed, you must establish andcontinuously monitor limits on threekey operating parameters that affectgood combustion: (1) Maximumhazardous waste feedrate; (2) minimumtemperature at the exit of eachcombustion chamber; and (3) residencetime in the combustion chamber asindicated by gas flowrate or kilnproduction rate. We have alsodetermined that you must establishappropriate monitoring requirements toensure that the operation of eachhazardous waste firing system ismaintained. We discuss each of theseparameters below.

i. Maximum Hazardous WasteFeedrate. You must establish andcontinuously monitor a maximumhazardous waste feedrate limit for

pumpable and nonpumpable wastes.See 61 FR at 17422. An increase inwaste feedrate without a correspondingincrease in combustion air can causeinefficient combustion that mayproduce (or incompletely destroy)dioxin/furan precursors. You must alsoestablish hazardous waste feedratelimits for each location where waste isfed.

One commenter suggests that there isno reason to limit the feedrate of eachfeedstream; a limit on the totalhazardous waste feedrate to eachcombustion chamber would be a moreappropriate control parameter. Weconcur in part. Limits are notestablished for each feedstream. Rather,limits apply to total and pumpablewastes feedrates for each feed location.Limits on pumpable wastes are neededbecause the physical form of the wastecan affect the rate of oxygen demandand thus combustion efficiency.Pumpable wastes often will expose agreater surface area per mass of wastethan nonpumpable wastes, thus creatinga more rapid oxygen demand. If thatdemand is not satisfied, inefficientcombustion will occur. We also notethat these waste feedrate limitrequirements are consistent with currentRCRA permitting requirements forhazardous waste combustors.

As proposed, you must establishhourly rolling average limits forhazardous waste feedrate fromcomprehensive performance test data asthe average of the highest hourly rollingaverages for each run. See Part Five,Section VII.B.3 above for the rationalefor this approach for calculating limitsfrom comprehensive performance testdata.

ii. Minimum Gas Temperature in theCombustion Zone. You must establishand continuously monitor limits onminimum gas temperature in thecombustion zone of each combustionchamber irrespective of whetherhazardous waste is fed into thechamber. See 61 FR at 17422. Theselimits are needed because, ascombustion zone temperatures decrease,combustion efficiency can decreaseresulting in increased formation of (orincomplete destruction of) dioxin/furanprecursors.224

Monitoring combustion zonetemperatures can be problematic,however, because the actual burningzone temperature cannot be measured atmany units (e.g., cement kilns). For thisreason, the BIF rule requires



225 The temperature limits apply to a combustionchamber even if hazardous waste is not burned inthe chamber for two reasons. First, an incineratormay rely on an afterburner that is fired with a fuelother than hazardous waste to ensure goodcombustion of organic compounds volatilized fromhazardous waste in the primary chamber. Second,MACT controls apply to total emissions (exceptwhere the rule makes specific provisions),irrespective of whether they derive from burninghazardous waste or other material, or from rawmaterials.

226 See USEPA. ‘‘Final Technical SupportDocument for Hazardous Waste Combustor MACTStandards, Volume IV: Compliance with theHazardous Waste Combustor Standards’’, February,1999, for further discussion.

227 We note that an increase in gas flowrate canalso adversely affect the performance of a dioxin/furan emission control device (e.g., carboninjection, catalytic oxidizer). Thus, gas flowrate iscontrolled for this reason as well.

228 See USEPA, ‘‘Final TSD for hazardous WasteCombustor MACT Standards, Volume IV:Compliance with the Hazardous Waste CombustorStandards’’, February, 1999 for further discussion.

measurement of the ‘‘combustionchamber temperature where thetemperature measurement is as close tothe combustion zone as possible.’’ See§ 266.103(c)(1)(vii). In some cases,temperature is measured at a locationquite removed from the combustionzone due to extreme temperatures andthe harsh conditions at the combustionzone. We discussed this issue atproposal and indicated that we wereconcerned that monitoring at suchremote locations may not accuratelyreflect changes in combustion zonetemperatures. See 61 FR at 17423.

We requested comment on possibleoptions to address the issue. Under oneoption, the final rule would haveallowed the source to identify aparameter that correlates withcombustion zone temperature and toprovide data or information to supportthe use of that parameter in theoperating record. Under another option,the final rule would have enabledregulatory officials on a case-specificbasis to require the use of alternateparameters as deemed appropriate, or todetermine that there is no practicableapproach to ensure that minimumcombustion chamber temperature ismaintained (and what the recourse/consequence would be).

Some commenters recommend thestatus quo as identified by the BIF rulerequirements for monitoring combustionzone temperature. These commenterssuggest that more prescriptiverequirements would not beimplementable for cement kilns becauseuse of the temperature measurementinstrumentation would simply not bepracticable under combustion zoneconditions in a cement kiln. We agreethat combustion zone temperaturemonitoring for certain types of sourcesrequires some site-specificconsiderations (as evidenced in oursecond proposed option discussedabove), and conclude that more specificlanguage than that used in the BIF ruleto address this issue would not beappropriate. Accordingly, we adoptlanguage similar to the BIF rule intoday’s final rule. You must measure thetemperature of each combustionchamber at a location that bestrepresents, as practicable, the bulk gastemperature in the combustion zone ofthat chamber. You are required toidentify the temperature measurementlocation and method in thecomprehensive performance test plan,which is subject to Agency approval.

The temperature limit(s) apply to eachcombustion zone, as proposed. See 61FR at 17423. For incinerators with aprimary and secondary chamber, youmust establish separate limits for the

combustion zone in each chamber.225

For kilns, you must establish separatetemperature limits at each locationwhere hazardous waste may be fired(e.g., the hot end where clinker isdischarged; and the upper end of thekiln where raw material is fed). We alsoproposed to include temperature limitsfor hazardous waste fired at the midkiln.One commenter indicates that it istechnically infeasible to measuretemperature directly at the midkilnwaste feeding location, however. Weagree that midkiln gas temperature isdifficult to measure due to the rotationof the kiln.226 Thus, the final rule allowstemperature measurement at the kilnback-end as a surrogate.

You must establish an hourly rollingaverage temperature limit based onoperations during the comprehensiveperformance test. The hourly rollingaverage limit is established as theaverage of the test run averages. See PartFive, Sections VII.B.1 and B.3 above fora discussion on the approach forcalculating limits from comprehensiveperformance test data.

iii. Maximum Flue Gas Rate or KilnProduction Rate. As proposed, you mustestablish and continuously monitor alimit on maximum flue gas flowrate or,as a surrogate, kiln production rate. See61 FR at 17423. Flue gas flowrates inexcess of those that occur duringcomprehensive performance testingreduce the time that combustion gasesare exposed to combustion chambertemperatures. Thus, combustionefficiency can decrease potentiallycausing an increase in dioxin/furanprecursors and, ultimately, dioxin/furanemissions.227

For cement kilns and lightweightaggregate kilns, the rule allows the useof production rate as a surrogate for fluegas flowrate. This is the approachcurrently used for the BIF rule for thesedevices, given that flue gas flowratecorrelates with production rate (e.g.,

feedrate of raw materials or rate ofproduction of clinker or aggregate).

At proposal, however, we expressedconcern that production rate may notrelate well to flue gas flowrate insituations where the moisture content ofthe feed to the combustor changesdramatically. See 61 FR at 17423. Somecommenters concur and also expressconcern that production rate is not areliable surrogate for flue gas flowratebecause changes in ambient temperaturecan cause increased heat rates andchanges in operating conditions canresult in variability in excess air rates.Based on an analysis of kiln processes,however, we conclude that these issuesshould not be a concern. With respectto changes in moisture content of thefeed, kilns tend to have a steady andhomogeneous waste and raw materialprocessing system. Thus, the feedmoisture content does not fluctuatewidely, and variation in moisturecontent of the stack does notsignificantly affect gas flowrate.228 Thus,production rate should be an adequatesurrogate for gas flowrate for ourpurposes here.

You must establish a maximum gasflowrate or production rate limit as theaverage of the maximum hourly rollingaverages for each run of thecomprehensive performance test. SeePart Five, Sections VII.B.3 above for therationale for the approach forcalculating limits from comprehensiveperformance test data.

iv. Operation of Each HazardousWaste Firing System. You mustrecommend in the comprehensiveperformance test plan that you submitfor review and approval operatingparameters, limits, and monitoringapproaches to ensure that eachhazardous waste firing system continuesto operate as efficiently as demonstratedduring the comprehensive performancetest.

It is important to maintain operationof the hazardous waste firing system atlevels of the performance test to ensurethat the same or greater surface area ofthe waste is exposed to combustionconditions (e.g., temperature andoxygen). Oxidation takes place morequickly and completely as the surfacearea per unit of mass of the wasteincreases. If the firing system were todegrade over time such that smallersurface area is exposed to combustionconditions, inefficient combustioncould result leading potentially to anincrease in dioxin/furan precursors.



229 Because incomplete combustion of fuels (e.g.,oil, coal, tires) could contribute to increased dioxin/furan emissions by producing dioxin/furanprecursors, permitting official may require (duringreview and approval of the comprehensiveperformance test plan) that you establish limits onoperating parameters for firing systems in additionto those firing hazardous waste.

At proposal, we discussedestablishing operating parameter limitsonly for minimum nozzle pressure andmaximum viscosity of wastes firedusing a liquid waste injection system. Indeveloping the final rule, however, wedetermined that RCRA permit writerscurrently establish operating parameterlimits on each waste firing system toensure compliance with the RCRAdestruction and removal efficiency(DRE) standard. We are continuing theDRE requirement as a MACT standard,and as discussed in Section VII.D.7below, the DRE operating parameterlimits are identical to those required tomaintain good combustion practices forcompliance with the dioxin/furanstandard. This is because compliancewith the DRE standard is ensured bymaintaining good combustion practices.Consequently, we include a requirementto establish limits on operatingparameters for each waste or fuel firingsystem as a measure of good combustionpractices for the dioxin/furan standardas well to be technically correct and forpurposes of completeness.229 Becausethis requirement is identical to anexisting RCRA requirement, it will notimpose an incremental burden.

The rule does not prescribe genericoperating parameters and how toidentify limits because, given the varietyof firing systems and waste and fuelproperties, they are better defined on asite-specific basis. Examples ofmonitoring parameters for a liquidwaste firing system would be, asproposed, minimum nozzle pressureestablished as an hourly rolling averagebased on the average of the minimumhourly rolling averages for each run,coupled with a limit on maximum wasteviscosity. The viscosity limit could bemonitored periodically based onsampling and analysis. Examples ofmonitoring parameters for a lance firingsystem for sludges could be minimumpressure established as discussed above,plus a limit on the solids content of thewaste.

v. Consideration of Restrictions onBatch Size, Feeding Frequency, andMinimum Oxygen Concentration. Weproposed site-specific limits onmaximum batch size, batch feedingfrequency, and minimum combustiongas oxygen concentration as additionalcompliance requirements to ensure goodcombustion practices. See 61 FR at

17423. After carefully considering allcomments, and for the reasonsdiscussed below, we conclude that thecarbon monoxide and hydrocarbonemission standards assure use of goodcombustion practices during batch feedoperations. This is because the carbonmonoxide and hydrocarbon CEMS arereliable and continuous indicators ofcombustion efficiency. In situationswhere batch feed operatingrequirements may be needed to betterassure good combustion practices,however, we rely on the permit writer’sdiscretionary authority under§ 63.1209(g)(2) to impose additionaloperating parameter limits on a site-specific basis.

Many hazardous waste combustorsburn waste fuel in batches, such asmetal drums or plastic containers. Somecontainerized waste can volatilizerapidly, causing a momentary oxygen-deficient condition that can result in anincrease in emissions of carbonmonoxide, hydrocarbon, and dioxin/furan precursors. We proposed to limitbatch size, batch feeding frequency, andminimum combustion gas oxygenconcentration to address this concern.

Commenters suggest that theproposed batch feed requirements (thatwould limit operations to the smallestbatch, the longest time interval, and themaximum oxygen concentrationdemonstrated during the comprehensiveperformance test) would result inextremely conservative limits thatwould severely limit a source’s ability tobatch-feed waste. Given these concernsand our reanalysis of the need for theselimits, we conclude that the carbonmonoxide and hydrocarbon emissionstandards will effectively ensure goodcombustion practices for most batchfeed operations. Consequently, the finalrule does not require limits for batchfeed operating parameters.

Carbon monoxide or hydrocarbonmonitoring may not be adequate for allbatch feed operations, however, toensure good combustion practices aremaintained. We anticipate thatpermitting officials will determine on asite-specific basis, typically duringreview of the initial comprehensiveperformance test plan, whether limitson one or more batch feed operatingparameters need to be established toensure good combustion practices aremaintained. This review shouldconsider your previous compliancehistory (e.g., frequency of automaticwaste feed cutoffs attributable to batchfeed operations that resulted in anexceedance of an operating limit orstandard under RCRA regulations priorto the compliance date), together withthe design and operating features of the

combustor. Providing permittingofficials the authority under§ 63.1209(g)(2) to establish batch feedoperating parameter limits only wherewarranted precludes the need to imposethe limits on all sources.

Permitting officials may alsodetermine that limits on batch feedoperating parameters are needed for aparticular source based on the frequencyof automatic waste feed cutoffs after theMACT compliance date. Permittingofficials would consider cutoffs that areattributable to batch feed operations andthat result in an exceedance of anoperating parameter limit or the carbonmonoxide or hydrocarbon emissionstandard. Given that you must notifypermitting officials if you have 10 ormore automatic waste feed cutoffs in a60-day period that result in anexceedance of an operating parameterlimit or CEMS-monitored emissionstandard, permitting officials shouldtake the opportunity to determine ifbatch feed operations contributed to thefrequency of exceedances. If so,permitting officials should use theauthority under § 63.1209(g)(2) toestablish batch feed operating parameterlimits.

Although we are not finalizing batchfeed operating parameter limits, weanticipate that permitting officials willrequire you (during review and approvalof the test plan) to simulate worst-casebatch feed operating conditions duringthe comprehensive performance testwhen demonstrating compliance withthe dioxin/furan and destruction andremoval efficiency standards. It wouldbe inappropriate for you to operate yourbatch feed system during thecomprehensive performance test in amanner that is not considered worst-case, considering the types andquantities of wastes you may burn, andthe range of values you may encounterduring operations for batch feed-relatedoperating parameters (e.g., oxygenlevels, batch size and/or btu content,waste volatility, batch feedingfrequency).

To ensure that the CEMS-monitoredcarbon monoxide and hydrocarbonemission standards ensure goodcombustion practices for batch feedoperations, the final rule includesspecial requirements to ensure that‘‘out-of-span’’ carbon monoxide andhydrocarbon CEMS readings areadequately accounted for. We proposedbatch feed operating parameter limits inpart because of concern that the carbonmonoxide and hydrocarbon CEMS maynot accurately calculate hourly rollingaverages when you encounter emissionconcentrations that exceed the span ofthe CEMS. This is an important



230 As explained in Part Five, Section VII.D.4 ofthe text, this concern is not limited to batch feedoperations.

231 A higher hourly rolling average carbonmonoxide level that is above the standard requiresa longer period of time to drop below the standard.

232 The carbon monoxide CEMS upper span levelfor the high range is 3000 ppmv. The upper spanlevel for hydrocarbon CEMS is 100 ppmv. (SeePerformance Specifications 4B and 8A in AppendixB, part 60, and the appendix to subpart EEE, part63—Quality Assurance Procedures for ContinuousEmissions Monitors Used for Hazardous WasteCombustors, Section 6.3).

233 You would not be required to assume theseone-minute values if you use a CEMS that meets theperformance specifications for a range that is higherthan the recorded one-minute average. In this case,the CEMS must meet performance specifications forthe higher range as well as the ranges specified inthe performance specifications in Appendix B, part60. See § 63.1209 (a)(3) and (a)(4).

234 We discuss below, however, that goodparticulate matter control is also required if asource is equipped with a carbon bed. This is toensure that particulate control upstream of thecarbon bed is maintained to performance test levelsto prevent blinding of the bed and loss of removalefficiency.

235 Examples of carbon properties include specificsurface area, pore volume, average pore size, poresize distribution, bulk density, porosity, carbonsource, impregnation, and activization procedure.See USEPA, ‘‘Technical Support Document forHWC MACT Standards, Volume IV: Compliancewith the HWC MACT Standards,’’ July 1999.

consideration because batch feedoperations have the potential to generatelarge carbon monoxide or hydrocarbonspikes—large enough at times to exceedthe span of the detector. When thisoccurs, the CEMS in effect ‘‘pegs out’’and the analyzer may only record dataat the upper end of its span, while infact carbon monoxide/hydrocarbonconcentrations are much higher. Inthese situations, the true carbonmonoxide/hydrocarbon concentration isnot being used to calculate the hourlyrolling average. This has two significantconsequences of concern to us.230

First, you could experience a largecarbon monoxide/hydrocarbon spike (asa result of feeding a large or highlyvolatile batch) which causes the monitorto ‘‘peg out.’’ In this situation, the CEMSwould record carbon monoxide/hydrocarbon levels that are lower thanactual levels. This under-reporting ofemission levels would result in anhourly rolling average that is biasedlow. You may in fact be exceeding theemission standard even though theCEMS indicates you are in compliance.Second, if a carbon monoxide/hydrocarbon excursion causes anautomatic waste feed cutoff, you may beallowed to resume hazardous wasteburning much sooner than you wouldbe allowed if the CEMS were measuringtrue hourly rolling averages. This isbecause you must continue monitoringoperating parameter limits and CEMS-monitored emission standards after anautomatic waste feed cutoff and youmay not restart hazardous waste feedinguntil all limits and CEMS-monitoredemission standards are withinpermissible levels.231

As explained in Part Five, SectionVII.D.4 below, we have resolved these‘‘out of span’’ concerns by includingspecial provisions in today’s rule forinstances when you encounterhydrocarbon/carbon monoxide CEMSmeasurements that are above the upperspan required by the performancespecifications.232 These specialprovisions require you to assumehydrocarbons and carbon monoxide arebeing emitted at levels of 500 ppmv and10,000 ppmv, respectively, when any

one minute average exceeds the upperspan level of the detector.233 Althoughwe did not propose these specialprovisions, they are a logical outgrowthof the proposed batch feed requirementsand commenters concerns about thoserequirements.

For the reasons discussed above, weconclude that national requirements forbatch feed operating parameter limitsare not warranted.

c. Activated Carbon Injection. If yourcombustor is equipped with anactivated carbon injection system, youmust establish and comply with limitson the following operating parameters:Good particulate matter control,minimum carbon feedrate, minimumcarrier fluid flowrate or nozzle pressuredrop, and identification of the carbonbrand and type or the adsorptioncharacteristics of the carbon. These arethe same compliance parameters that weproposed. See 61 FR at 17424.

i. Good Particulate Matter Control.You must comply with the operatingparameter limits for particulate mattercontrol (see discussion in SectionVII.D.6 below and § 63.1209(m)) becausecarbon injection controls dioxin/furanin conjunction with particulate mattercontrol. Dioxin/furan is adsorbed ontocarbon that is injected into thecombustion gas, and the carbon isremoved from stack gas by a particulatecontrol device.

Although we proposed to requiregood particulate matter control as acontrol technique for dioxin/furanirrespective of whether carbon injectionwas used, commenters indicate that wehave no data demonstrating therelationship between particulate matterand dioxin/furan emissions.Commenters further indicate thatdioxin/furan occur predominately in thegas phase, not adsorbed ontoparticulate. We agree with commentersthat hazardous waste combustorsoperating under the good combustionpractices required by this final rule arenot likely to have significant carbonparticulates in stack gas (i.e., becausecarbonaceous particulates (soot) areindicative of poor combustionefficiency). Thus, unless activatedcarbon injection is used as a controltechnique, dioxin/furan will occurpredominately in the gas phase. Wetherefore conclude that requiring goodparticulate control as a control

technique for dioxin/furan is notwarranted unless a source is equippedwith activated carbon injection.234

ii. Minimum Carbon Feedrate. Asproposed, you must establish andcontinuously monitor a limit onminimum carbon feedrate to ensure thatdioxin/furan removal efficiency ismaintained. You must establish anhourly rolling average feedrate limitbased on operations during thecomprehensive performance test. Thehourly rolling average limit isestablished as the average of the test runaverages. See Part Five, Sections VII.B.1and B.3 above for a discussion of theapproach for calculating limits fromcomprehensive performance test data.

iii. Minimum Carrier Fluid Flowrateor Nozzle Pressure Drop. A carrier fluid,gas or liquid, is necessary to transportand inject the carbon into the gasstream. As proposed, you must establishand continuously monitor a limit oneither minimum carrier fluid flowrate orpressure drop across the nozzle toensure that the flow and dispersion ofthe injected carbon into the flue gasstream is maintained.

We proposed to require you to basethe limit on the carbon injectionmanufacturer’s specifications. Onecommenter notes that there are nomanufacturer specifications for carriergas flowrate or pressure drop. Therefore,the final rule allows you to useengineering information and principlesto establish the limit for minimumcarrier fluid flowrate or pressure dropacross the injection nozzle. You mustidentify the limit and the rationale forderiving it in the comprehensiveperformance test plan that you submitfor review and approval.

iv. Identification of Carbon Brand andType or Adsorption Properties. Youmust either identify the carbon brandand type used during thecomprehensive performance test andcontinue using that carbon, or identifythe adsorption properties of that carbonand use a carbon having equivalent orbetter properties. This will ensure thatthe carbon’s adsorption properties aremaintained.235

We proposed to require you to use thesame brand and type of carbon that was



236 We have incorporated the alternativemonitoring provisions of § 63.8(f) in § 63.1209(g)(1)so that alternative monitoring provisions for

nonCEMS CMS can be implemented by authorizedStates. The alternative monitoring provisions of§ 63.1209(g)(1) do not apply to CEMS, however. Thealternative monitoring provisions of § 63.8(f)continue to apply to CEMS because implementationof those provisions is not eligible to be delegatedto States at this time.

used during the comprehensiveperformance test. Commenters object tothis requirement and suggest that theyshould have the option of usingalternative types of carbon that wouldachieve equivalent or betterperformance than the carbon usedduring the performance test. We concur,and the final rule allows you todocument in the comprehensiveperformance test plan key parametersthat affect adsorption and the limits youhave established on those parametersbased on the carbon to be used duringthe performance test. You maysubstitute at any time a different brandor type of carbon provided that thereplacement has equivalent or improvedproperties and conforms to the keysorbent parameters you have identified.You must include in the operatingrecord written documentation that thesubstitute carbon will provide the samelevel of control as the original carbon.

d. Activated Carbon Bed. If yourcombustor is equipped with anactivated carbon bed, you must establishand comply with limits on the followingoperating parameters: good particulatematter control; maximum age of eachcarbon bed segment; identification ofcarbon brand and type or adsorptionproperties, and maximum temperatureat the inlet or exit of the bed. These arethe same compliance parameters that weproposed. See 61 FR at 17424.

i. Good Particulate Matter Control.You must comply with the operatingparameter limits for particulate mattercontrol (see discussion in SectionVII.D.6 below and § 63.1209(m)). If goodcontrol of particulate matter is notmaintained prior to the inlet to thecarbon bed, particulate matter couldcontaminate the bed and affect dioxin/furan removal efficiency. In addition, ifparticulate matter control is useddownstream from the carbon bed, thosecontrols must conform to goodparticulate matter control. This isbecause this ‘‘polishing’’ particulatematter control device may capturecarbon-containing dioxin/furan thatmay escape from the carbon bed. Thus,the efficiency of this polishing controlmust be maintained to ensurecompliance with the dioxin/furanemission standard.

ii. Maximum Age of Each BedSegment. As proposed, you mustestablish a maximum age of each bedsegment to ensure that removalefficiency is maintained. Becauseactivated carbon removes dioxin/furan(and mercury) by adsorption, carbon inthe bed becomes less effective over timeas the active sites for adsorption becomeoccupied. Thus, bed age is an importantoperating parameter.

At proposal, we requested commenton using carbon aging or some form ofa breakthrough calculation to identify alimit on carbon age. See 61 FR at 17424.A breakthrough calculation would givea theoretical minimum carbon change-out schedule that you could use toensure that breakthrough (i.e., thedramatic reduction in efficiency of thecarbon bed due to too many active sitesbeing occupied) does not occur.

Commenters indicate that carboneffectiveness depends on the carbon bedage and pollutant types andconcentrations in the gas streams, andtherefore a carbon change-out scheduleshould be based on a breakthroughcalculation rather than carbon age. Weagree that a breakthrough calculationmay be a better measurement of carboneffectiveness, but it would be difficult todefine generically for all situations. Abreakthrough calculation could beperformed only after experimentationdetermines the relationship betweenincoming adsorbed chemicals and theadsorption rate of the carbon. Theadsorption rate of carbon could bedetermined experimentally, but thespeciation of adsorbed chemicals in aflue gas stream is site-specific and mayvary greatly at a given site over time.

We conclude that because carbon agecontributes to carbon ineffectiveness, itserves as an adequate surrogate and isless difficult to implement on a nationalbasis. Therefore, the rule requiressources to identify maximum carbon ageas the maximum age of each bedsegment during the comprehensiveperformance test. Carbon age ismeasured in terms of the cumulativevolume of combustion gas flow throughthe carbon since its addition to the bed.Sources may use the manufacturer’sspecifications rather than actual bed ageduring the initial comprehensiveperformance test to identify the initiallimit on maximum bed age. If you electto use manufacturer’s specifications forthe initial limit on bed age, you mustalso recommend in the comprehensiveperformance test plan submitted forreview and approval a schedule ofdioxin/furan testing prior to theconfirmatory performance test that willconfirm that the manufacturer’sspecification of bed age is sufficient toensure that you maintain compliancewith the emission standard.

If either existing or new sources preferto use some form of breakthroughcalculation to establish maximum bedage, you may petition permittingofficials under § 63.1209(g)(1) 236 to

apply for an alternative monitoringscheme.

iii. Identification of Carbon Brand andType or Adsorption Properties. Youmust either identify the carbon brandand type used during thecomprehensive performance test andcontinue using that carbon, or identifythe adsorption properties of that carbonand use a carbon having equivalent orbetter properties. This requirement isidentical to that discussed above foractivated carbon injection systems.

iv. Maximum Temperature at the Inletor Exit of the Bed. You must establishand continuously monitor a limit on themaximum temperature at the inlet orexit of the carbon bed. This is becausea combustion gas temperature spike cancause adsorbed dioxin/furan (andmercury) to desorb and reenter the gasstream. In addition, the adsorptionproperties of carbon are adverselyaffected at higher temperatures.

At proposal, we requested commenton whether it would be necessary tocontrol temperature at the inlet to thecarbon bed. See 61 FR at 17425. Somecommenters support temperaturecontrol noting the concern thattemperature spikes could causedesorption of dioxin/furan (andmercury). We concur, and are requiringyou to establish a maximumtemperature limit at the inlet or exit ofthe bed. We are allowing you the optionof measuring temperature at either endof the bed to give you greater flexibilityin locating the temperature continuousmonitoring system. Monitoringtemperature at either end of the bedshould be adequate to ensure that bedtemperatures are maintained at levelsnot exceeding those during thecomprehensive performance test(because the temperature remainsrelatively constant across the bed).

You must establish an hourly rollingaverage temperature limit based onoperations during the comprehensiveperformance test. The hourly rollingaverage limit is established as theaverage of the test run averages. See PartFive, Sections VII.B.1 and B.3 above fora discussion of the approach forcalculating limits from comprehensiveperformance test data.

e. Catalytic Oxidizer. If yourcombustor is equipped with a catalyticoxidizer, you must establish and complywith limits on the following operatingparameters: minimum gas temperature



at the inlet of the catalyst; maximum agein use; catalyst replacementspecifications; and maximum flue gastemperature at the inlet of the catalyst.These are the same complianceparameters that we proposed. See 61 FRat 17425.

Catalytic oxidizers used to controlstack emissions are similar to those usedin automotive and industrialapplications. The flue gas passes overcatalytic metals, such as palladium andplatinum, supported by an aluminawashcoat on some metal or ceramicsubstrate. When the flue gas passesthrough the catalyst, a reaction takesplace similar to combustion, convertinghydrocarbons to carbon monoxide, thencarbon dioxide. Catalytic oxidizers canalso be ‘‘poisoned’’ by lead and othermetals in the same manner asautomotive and industrial catalysts.

i. Minimum Gas Temperature at theInlet of the Catalyst. You must establishand continuously monitor a limit on theminimum flue gas temperature at theinlet of the catalyst to ensure that thecatalyst is above light-off temperature.Light-off temperature is that minimumtemperature at which the catalyst is hotenough to catalyze the reactions ofhydrocarbons and carbon monoxide.

You must establish an hourly rollingaverage temperature limit based onoperations during the comprehensiveperformance test. The hourly rollingaverage limit is established as theaverage of the test run averages.

ii. Maximum Time In-Use. You mustestablish a limit on the maximum timein-use of the catalyst because a catalystis poisoned and generally degraded overuse. You must establish the limit basedon the manufacturer’s specifications.

iii. Catalytic Metal Loading,Maximum Space-Time, and SubstrateConstruct. When you replace a catalyst,the replacement must be of the samedesign to ensure that destructionefficiency is maintained. Consequently,the rule requires that you specify thefollowing catalyst properties: Loading ofcatalytic metals; space-time; andmonolith substrate construction.

Catalytic metal loading is importantbecause, without sufficient catalyticmetal on the catalyst, it does notfunction properly. Also, some catalyticmetals are more efficient than others.Therefore, the replacement catalystmust have at least the same catalyticmetal loading for each catalytic metal asthe catalyst used during thecomprehensive performance test.

Space-time, expressed in inverseseconds (s-1), is defined as the maximumrated volumetric flow through thecatalyst divided by the volume of thecatalyst. This is important because it is

a measure of the gas flow residence timeand, hence, the amount of time the fluegas is in the catalyst. The longer the gasis in the catalyst, the more time thecatalyst has to cause hydrocarbons andcarbon monoxide to react. Replacementcatalysts must have the same or lowerspace-time as the one used during thecomprehensive performance test.

Substrate construction is also animportant parameter affectingdestruction efficiency of the catalyst.Three factors are important. First,substrates for industrial applications aretypically monoliths, made of rippledmetal plates banded together around thecircumference of the catalyst. Ceramicmonoliths and pellets can also be used.Because of the many types of substrates,you must use the same materials ofconstruction, monolith or pellets andmetal or ceramic, used during thecomprehensive performance test asreplacements. Second, monoliths form ahoneycomb like structure when viewedfrom one end. The pore density (i.e.,number of pores per square inch) iscritical because the pores must be smallenough to ensure intimate contactbetween the flue gas and the catalyst butlarge enough to allow unrestricted flowthrough the catalyst. Therefore, if youuse a monolith substrate during thecomprehensive performance test, thereplacement catalyst must have thesame pore density. Third, catalysts aresupported by a washcoat, typicallyalumina. We require that replacementcatalysts have the same type andloading of washcoat as was on thecatalyst used during the comprehensiveperformance test.

iv. Maximum Flue Gas Temperatureat the Inlet to the Catalyst. You mustestablish and continuously monitor alimit on maximum flue gas temperatureat the inlet to the catalyst. Inlettemperature is important becausesustained high flue gas temperature canresult in sintering of the catalyst,degrading its performance. You mustestablish the limit as an hourly rollingaverage, based on manufacturerspecifications.

In the proposed rule, we would haveallowed a waiver from these operatingparameter limits if you documented tothe Administrator that establishinglimits on other operating parameterswould be more appropriate to ensurethat the dioxin/furan destructionefficiency of the oxidizer is maintainedafter the performance test. See 61 FR at17425. We are not finalizing a specificwaiver for catalytic oxidizer parametersbecause you are eligible to apply for thesame relief under the existingalternative monitoring provisions of§ 63.1209(g)(1).

f. Dioxin/Furan Formation Inhibitor.If you feed a dioxin/furan formationinhibitor into your combustor as anadditive (e.g., sulfur), you must: (1)Establish a limit on minimum inhibitorfeedrate; and (2) identify either thebrand and type of inhibitor or theproperties of the inhibitor.

i. Minimum Inhibitor Feedrate. Asproposed, you must establish andcontinuously monitor a limit onminimum inhibitor feedrate to helpensure that dioxin/furan formationreactions continue to be inhibited atlevels of the comprehensiveperformance test. See 61 FR at 17425.You must establish an hourly rollingaverage feedrate limit based onoperations during the comprehensiveperformance test. The hourly rollingaverage limit is established as theaverage of the test run averages.

This minimum inhibitor feedratepertains to additives to feedstreams, notnaturally occurring inhibitors that maybe found in fossil fuels, hazardouswaste, or raw materials. At proposal, werequested comment on whether it wouldbe appropriate to establish feedratelimits on the amount of naturallyoccurring inhibitors based on levels fedduring the comprehensive performancetest. See 61 FR at 17425. For example,it is conceivable that a source wouldchoose to burn high sulfur fuel or wasteonly during the comprehensiveperformance test and then switch backto low sulfur fuels or waste after thetest, thus reducing dioxin/furanemissions during the comprehensivetest to levels that would not bemaintained after the test. Commentersdo not provide information on thismatter and we do not have enoughinformation on the types or effects ofnaturally occurring substances that mayact as inhibitors. Therefore, the finalrule does not establish limits onnaturally occurring inhibitors.Permitting officials, however, maychoose to address the issue of naturallyoccurring inhibitors when warrantedduring review of the comprehensiveperformance test plan. (Seediscretionary authority of permittingofficials under § 63.1209(g)(2) to imposeadditional or alternative operatingparameter limits on a site-specificbasis.)

ii. Identification of Either the Brandand Type of Inhibitor or the Propertiesof the Inhibitor. As proposed, you musteither identify the inhibitor brand andtype used during the comprehensiveperformance test and continue usingthat inhibitor, or identify the propertiesof that inhibitor that affect its ability toinhibit dioxin/furan formation reactionsand use an inhibitor having equivalent



237 See discussion in Section VII.D.3. below in thetext for rationale for exempting these feedstreamsfor monitoring for mercury content.

or better properties. This requirement isidentical to that discussed above foractivated carbon systems.

2. What Are the Operating ParameterLimits for Mercury?

You must maintain compliance withthe mercury emission standard byestablishing and complying with limitson operating parameters. See

§ 63.1209(l). The following tablesummarizes these operating parameterlimits. All sources must comply withthe limits on mercury feedrate. Otheroperating parameter limits apply if youuse the mercury control technique towhich they apply.

Mercury emissions from hazardouswaste combustors are controlled bycontrolling the feedrate of mercury, wetscrubbing to remove soluble mercuryspecies (e.g, mercuric chloride), andcarbon adsorption. We discuss belowthe operating parameter limits thatapply to each control technique. Wealso discuss why we are not limiting thetemperature at the inlet to the dryparticulate matter control device as acontrol parameter for mercury.

a. Maximum Mercury Feedrate. Asproposed, you must establish andcomply with a maximum total feedratelimit for mercury for all feedstreams.See 61 FR at 17428. The amount ofmercury fed into the combustor directlyaffects emissions and the removalefficiency of emission controlequipment. To establish and complywith the feedrate limit, you must sampleand analyze and continuously monitorthe flowrate of all feedstreams(including hazardous waste, rawmaterials, and other fuels and additives)except natural gas, process air, andfeedstreams from vapor recoverysystems for mercury content.237 As

proposed, you must establish amaximum 12-hour rolling averagefeedrate limit based on operationsduring the comprehensive performancetest as the average of the test runaverages.

Rather than establish mercuryfeedrate limits as the levels fed duringthe comprehensive performance test,you may request as part of yourperformance test plan to use themercury feedrates and associatedemission rates during the performancetest to extrapolate to higher allowablefeedrate limits and emission rates. SeeSection VII.D.3 below for a discussion ofthe rationale and procedures forobtaining approval to extrapolate metalfeedrates.

In addition, you may use theperformance test waiver provisionunder § 63.1207(m) to documentcompliance with the emission standard.Under that provision, you must monitorthe total mercury feedrate from allfeedstreams and the gas flowrate anddocument that the maximum theoreticalemission concentration does not exceedthe mercury emission standard. Thus,this is another compliance approachwhere you would not establish feedratelimits on mercury during thecomprehensive performance test.

b. Wet Scrubbing. As proposed, ifyour combustor is equipped with a wetscrubber, you must establish andcomply with limits on the sameoperating parameters (and in the samemanner) that apply to complianceassurance with the hydrochloric acid/chlorine gas emission standard for wetscrubbers. See Section VII.D.5 below fora discussion of those parameters.

c. Activated Carbon Injection. Asproposed, if your combustor is equippedwith an activated carbon injectionsystem, you must establish and complywith limits on the same operatingparameters (and in the same manner)that apply to compliance assurance withthe dioxin/furan emission standard foractivated carbon injection systems.

d. Activated Carbon Bed. Asproposed, if your combustor is equippedwith an activated carbon bed, you mustestablish and comply with limits on thesame operating parameters (and in thesame manner) that apply to complianceassurance with the dioxin/furanemission standard for activated carbonbeds.

e. Consideration of a Limit onMaximum Inlet Temperature to a DryParticulate Matter Control Device. Thefinal rule does not require you to controlinlet temperature to a dry particulate



matter air pollution control device tocontrol mercury emissions. At proposal,we expressed concern that high inlettemperatures to a dry particulate mattercontrol device could cause low mercuryremoval efficiency because mercuryvolatility increases with increasingtemperature. See 61 FR at 17428.Therefore, we proposed to limit inlettemperatures to levels during thecomprehensive performance test.

Commenters suggest that a maximuminlet temperature for dry particulatematter control devices is not neededbecause mercury is generally highlyvolatile within the range of inlettemperatures of all dry particulatematter control devices. We arepersuaded by the commenters that inlet

temperature to these devices is notcritically important to mercury control,although temperature can potentiallyhave an impact on the volatility ofcertain mercury species (e.g., oxides).We conclude that the other operatingparameter limits are sufficient to ensurecompliance with the mercury emissionstandard. In particular, we note that alimit on maximum inlet temperature tothese control devices is required forcompliance assurance with the dioxin/furan, semivolatile metal, and lowvolatile metal emission standards.

3. What Are the Operating ParameterLimits for Semivolatile and LowVolatile Metals?

You must maintain compliance withthe semivolatile metal and low volatilemetal emission standards byestablishing and complying with limitson operating parameters. See§ 63.1209(n). The following tablesummarizes these operating parameterlimits. All sources must comply withthe limits on feedrates of semivolatilemetals, low volatile metals, andchlorine. Other operating parameterlimits apply depending on the type ofparticulate matter control device youuse.BILLING CODE 6560–50–P






238 See USEPA., ‘‘Technical Support Documentfor HWC MACT Standards, Volume IV: Compliancewith the MACT Standards,’’ February 1998.

239 This is because a greater portion ofsemivolatile metals volatilize in the combustionchamber and condenses in the flue gas on smallparticulates or as fume. The major portion of lowvolatile metals in flue gas are entrained on largerparticulates (rather than condensing from volatilespecies) and are thus easier to remove with aparticulate control device.

240 Although this extrapolation discussion ispresented in context of semivolatile and lowvolatile metal feedrates, similar provisions could beimplemented for mercury feedrates.

Semivolatile and low volatile metalemissions from hazardous wastecombustors are controlled by controllingthe feedrate of the metals andparticulate matter emissions. Inaddition, because chlorine feedrate canaffect the volatility of metals and thusmetals levels in the combustion gas, andbecause the temperature at the inlet tothe dry particulate matter control devicecan affect whether the metal is in thevapor (gas) or solid (particulate) phase,control of these parameters is alsoimportant to control emissions of thesemetals. We discuss below the operatingparameter limits that apply to eachcontrol technique. We also discuss useof metal surrogates during performancetesting, provisions for allowingextrapolation of performance testfeedrate levels to calculate metalfeedrate limits, and conditional waiverof the limit on low volatile metals inpumpable feedstreams.

a. Good Particulate Matter Control. Asproposed, you must comply with theoperating parameter limits forparticulate matter control (seediscussion in Section VII.D.6 below and§ 63.1209(m)) because semivolatile andlow volatile metals are primarily in thesolid (particulate) phase at the gastemperature (i.e., 400°F or lower) of theparticulate matter control device. Thus,these metals are largely removed fromflue gas as particulate matter.

b. Maximum Inlet Temperature to DryParticulate Matter Control Device. Asproposed, you must establish andcontinuously monitor a limit on themaximum temperature at the inlet to adry particulate matter control device.Although most semivolatile and lowvolatile metals are in the solid,particulate phase at the temperature atthe inlet to the dry control devicemandated by today’s rule (i.e., 400°F orlower), some species of these metalsremain in the vapor phase. We arerequiring a limit on maximumtemperature at the inlet to the controldevice to ensure that the fraction ofthese metals that are volatile (and thusnot controlled by the particulate mattercontrol device) does not increase duringoperations after the comprehensiveperformance test.

As proposed, you must establish anhourly rolling average temperature limitbased on operations during thecomprehensive performance test. Thehourly rolling average limit isestablished as the average of the test runaverages. See Part Five, Sections VII.B.1and B.3 above for a discussion of theapproach for calculating limits fromcomprehensive performance test data.

Commenters suggest that this limitmay conflict with the maximum

temperature limit at the inlet to theparticulate matter control device that isalso required for compliance assurancewith the dioxin/furan emissionstandard. We do not understandcommenters’ concern. If for some reasonthe dioxin/furan and metals emissionstests are not conducted simultaneously,the governing temperature limit will bethe lower of the limits established fromthe separate tests. This providescompliance assurance for bothstandards.

c. Maximum Semivolatile and LowVolatile Metals Feedrate Limits. Youmust establish limits on the maximumtotal feedrate of both semivolatile metalsand low volatile metals from allfeedstreams at levels fed during thecomprehensive performance test. Metalsfeedrates are related to emissions inthat, as metals feedrates increase at asource, metals emissions increase. SeePart Four, Section II.A above fordiscussion on the relationship betweenmetals feedrates and emissions. Thus,metals feedrates are an importantcontrol technique.

For low volatile metals, you must alsoestablish a limit on the maximum totalfeedrate of pumpable liquids from allfeedstreams. The rule requires aseparate limit for pumpable feedstreamsbecause metals present in pumpablefeedstreams may partition between thecombustion gas and bottom ash (or kilnproduct) at a higher rate than metals innonpumpable feedstreams (i.e., lowvolatile metals in pumpable feedstreamstend to partition primarily to thecombustion gas). The rule does notrequire a separate limit for semivolatilemetals in pumpable feedstreamsbecause partitioning between thecombustion gas and bottom ash orproduct for these metals does not appearto be affected by the physical state of thefeedstream.238

To establish and comply with thefeedrate limits, you must sample andanalyze and continuously monitor theflowrate of all feedstreams (includinghazardous waste, raw materials, andother fuels and additives) except naturalgas, process air, and feedstreams fromvapor recovery systems for semivolatileand low volatile metals content. Asproposed, you must establish maximum12-hour rolling average feedrate limitsbased on operations during thecomprehensive performance test as theaverage of the test run averages.

i. Use of Metal Surrogates. You mayuse one metal within a volatility groupas a surrogate during comprehensive

performance testing for other metals inthat volatility group. For example, youmay use chromium as a surrogate duringthe performance test for all low volatilemetals. Similarly, you may use lead asa surrogate for cadmium, the othersemivolatile metal. This is because themetals within a volatility group havegenerally the same volatility. Thus, theywill generally be equally difficult tocontrol with an emissions controldevice.

In addition, you may use eithersemivolatile metal as a surrogate for anylow volatile metal because semivolatilemetals will be more difficult to controlthan low volatile metals.239 This willhelp alleviate concerns regarding theneed to spike each metal duringcomprehensive performance testing. Ifyou want to spike metals, you need notspike each metal to comply with today’srule but only one metal within avolatility group (or potentially onesemivolatile metal for both volatilitygroups).

ii. Extrapolation of Performance TestFeedrate Levels to Calculate MetalFeedrate Limits.240 You may requestunder § 63.1209(n)(2)(ii) to use themetal feedrates and emission ratesassociated with the comprehensiveperformance test to extrapolate feedratelimits and emission rates at levelshigher than demonstrated during theperformance test. Extrapolation can beadvantageous because it avoids much ofthe spiking that sources normallyundertake during compliance testingand the associated costs, risks tooperating and testing personnel, andenvironmental loading from emissions.

Under an approved extrapolationapproach, you would be required to feedmetals at no less than normal rates tonarrow the amount of extrapolationrequested. Further, we expect that somespiking would be desired to increaseconfidence in the measured,performance test feedrate levels thatwill be used to project feedrate limits(i.e., the errors associated with samplingand analyzing heterogeneousfeedstreams can be minimized byspiking known quantities).Extrapolation approaches that requestfeedrate limits that are significantlyhigher than the historical range of



241 See USEPA, ‘‘Draft Technical SupportDocument for HWC MACT Standards (NODA),Volume III: Evaluation of Metal Emissions Databaseto Investigate Extrapolation and InterpolationIssues,’’ April 1997.

242 We plan to develop guidance on approachesthat provide greater flexibility.

feedrates should not be approved.Extrapolated feedrate limits should belimited to levels within the range of thehighest historical feedrates for thesource. We are taking this policyposition to avoid creating an incentiveto burn wastes with higher thanhistorical levels of metals. Metals arenot destroyed by combustion but ratherare emitted as a fraction of the amountfed to the combustor. If you want toburn wastes with higher than historicallevels of metals, you must incur thecosts and address the hazards to plantpersonnel and testing crews associatedwith spiking metals into yourfeedstreams during comprehensiveperformance testing.

Although we also investigateddownward interpolation (i.e., betweenthe measured feedrate and emissionlevel and zero), we are concerned thatdownward interpolation may not beconservative. Our data indicates thatsystem removal efficiency can decreaseas metal feedrate decreases. Thus, actualemissions may be higher than emissionsprojected by interpolation for lowerfeedrates. Consequently, we are notallowing downward interpolation.

We are not specifying anextrapolation methodology to provide asmuch flexibility as possible to considerextrapolation methodologies that wouldbest meet individual needs. We haveinvestigated extrapolationapproaches 241 and discussed in the May1997 NODA a statistical extrapolationmethodology. Commenters raiseconcerns, however, about defining asingle acceptable extrapolation method.They note that other methods might bedeveloped in the future that prove to bebetter, especially for a given source. Weagree that the approach discussed in theNODA may be too inflexible and are notpromulgating it today.242 Consequently,today’s rule does not specify a singlemethod but allows you to recommend amethod for review and approval bypermitting officials.

Your recommended extrapolationmethodology must be included in theperformance test plan. See§ 63.1207(f)(1)(x). Permitting officialswill review the methodologyconsidering in particular whether: (1)Performance test metal feedrates areappropriate (i.e., whether feedrates areat least at normal levels, whether somelevel of spiking would be appropriatedepending on the heterogeneity of the

waste, and whether the physical formand species of spiked material isappropriate); and (2) the requested,extrapolated feedrates are warrantedconsidering historical metal feedratedata.

We received comments both in favorof and in opposition to metalsextrapolation and interpolation. Thosein favor suggest extrapolation wouldsimplify the comprehensiveperformance test procedure, reducecosts, and decrease emissions duringtesting. Those in opposition areconcerned about: (1) Whether there is apredictable relationship betweenfeedrates and emission rates; (2) thepossibility of higher overall metalsloading to the environment over the lifeof the facility (i.e., because higherfeedrate limits would be relatively easyto obtain); (3) the difficulty in defininga ‘‘normal’’ feedrate for facilities withvariable metal feeds; and (4) whether allconditions influencing potential metalsemissions, such as combustiontemperature and metal compoundspeciation, could be adequatelyconsidered.

Given the pros and cons associatedwith various extrapolationmethodologies and policies, we are stillconcerned that sources would be ableto: (1) Feed metals at higher rateswithout a specific compliancedemonstration of the associated metalsemissions; and (2) obtain approval tofeed metals at higher levels than normal,even though all combustion sourcesshould be trying to minimize metalsfeedrates. However, because thealternative is metal spiking (asevidenced in facility testing for BIFcompliance) and metal spiking is asignificant concern as well, we find thatthe balance is better struck by allowing,with site-specific review and wherewarranted approval, extrapolation as ameans to reduce unnecessary emissions,reduce unnecessary costs incurred byfacilities, and better protect the health oftesting personnel during performancetests.

iii. Conditional Waiver of Limit onLow Volatile Metals in PumpableFeedstreams. Commenters indicate thatthey may want to base feedrate limitsonly on the worst-case feedstream—pumpable hazardous waste. Thefeedrate limit would be based only onthe feedrate of the pumpable hazardouswaste during the comprehensiveperformance test, even thoughnonpumpable feedstreams would becontributing some metals to emissions.In this situation, commenters suggestthat separate feedrate limits for total andpumpable feedstreams would not beneeded. We agree that if you define the

total feedstream feedrate limit as thepumpable feedstream feedrate duringthe performance test, dual limits are notrequired. The feedrate of metals in totalfeedstreams must be monitored andshown to be below the pumpablefeedstream-based limit. See§ 63.1209(n)(2)(C).

iv. Response to other Comments. Wediscuss below our response to severalother comments: (1) Recommendationfor national uniform feedrate limits; (2)concerns that feedstream monitoring isproblematic; and (3) recommendationsthat monitoring natural gas and vaporrecovery system feedstreams isunnecessary.

A commenter states that nationallyuniform feedrate limits are needed formetals and chlorine and that any otherapproach would be inconsistent withthe CAA. The commenter stated thathazardous waste combustion deviceoperators should not be allowed to self-select any level of toxic metal feedratejust because they can show compliancewith the MACT standard. We believethat standards prescribing nationalfeedrate limits on metals or chlorine arenot necessary to ensure MACT controlof metals and hydrochloric acid/chlorine gas and may be overlyrestrictive. Emissions of metals andhydrochloric acid/chlorine gas arecontrolled by controlling the feedrate ofmetals and chlorine, and emissioncontrol devices. In developing MACTstandards for a source category, if wecan identify emission levels that arebeing achieved by the best performingsources using MACT control, wegenerally establish the MACT standardas an emission level rather thanprescribed operating limits (e.g.,feedrate limits). This approach ispreferable because it gives the sourcethe option of determining the most cost-effective measures to comply with thestandard. Some sources may elect tocomply with the emission standardsusing primarily feedrate control, whileothers may elect to rely primarily onemission controls. Under eitherapproach, the emission levels areequivalent to those being achieved bythe best performing existing sources.Other factors that we considered indetermining to express the standards asan emission level rather than feedratelimits include: (1) There is not a single,universal correlation factor betweenfeedrate and metal emissions to use todetermine a national feedrate thatwould be equivalent to the emissionlevels achieved by the best performingsources; (2) emission standardscommunicate better to the public thatmeaningful controls are being appliedbecause the hazardous waste combustor



243 As discussed previously in the text, feedratelimits as a compliance tool can be problematic fordifficult to sample or analyze feedstreams. Further,the emissions resulting from a given feedrate levelmay increase (or decrease) over time, providinguncertainty about actual emissions.

emission standards can be compared tostandards for other waste combustors(e.g., municipal and medical wastecombustors) and combustion devices;and (3) CEMS, the ultimate complianceassurance tool that we encouragesources to use,243 are incompatible withstandards expressed as feedrate limits.

Another commenter is concerned thatfeedrate monitoring of highlyheterogeneous waste streams isproblematic and analytical turnaroundtimes can be rather long. Thecommenter suggests that alternativesbeyond feedstream monitoring (such aspredictive emissions monitoring) shouldbe allowed. Although we acknowledgethat there may be difficulties inmonitoring the feedrate of metals orchlorine in certain waste streams, theregenerally is no better way to assurecompliance with these standards otherthan using CEMS. Predictive modelingappears to introduce unnecessarilysome greater compliance uncertaintythan feedstream testing. Thus, weconclude that feedstream monitoring isa necessary monitoring tool if amultimetals CEMS is not used. (We alsonote that feedstream monitoring underMACT will not be substantially moreburdensome or problematic than therequirements now in place under RCRAregulations.)

In addition, another commentersuggests that sources should not have tomonitor metals and chlorine in naturalgas feedstreams because it is impracticaland levels are low and unvarying. Thecommenter suggests that sources shouldbe allowed to use characterization datafrom natural gas vendors. We agree thatthe cost and possible hazards ofmonitoring natural gas for metals andchlorine is not warranted because ourdata shows metals are not present atlevels of concern. Therefore, you are notrequired to monitor metals and chlorinelevels in natural gas feedstreams.However, you must document in thecomprehensive performance test planthe expected levels of these constituentsand account for the expected levels indocumenting compliance with feedratelimits (e.g., by assuming worst-caseconcentrations and monitoring thenatural gas flowrate). See§ 63.1209(c)(5).

Finally, some commenters areconcerned that feedstreams from vaporrecovery systems (e.g., waste fuel tankand container emissions) are difficult,costly, and often dangerous to monitor

frequently for metals and chlorinelevels. Particularly because of some ofthe safety issues concerned, the ruledoes not require continuous monitoringof metals and chlorine for feedstreamsfrom vapor recovery systems. However,as is the case for natural gas, you mustdocument in the comprehensiveperformance test plan the expectedlevels of these constituents and accountfor the expected levels in documentingcompliance with feedrate limits.

d. Maximum Chlorine Feedrate. Asproposed, you must establish a limit onthe maximum feedrate for total chlorine(both organic and inorganic) in allfeedstreams based on the level fedduring the comprehensive performancetest. A limit on maximum chlorinefeedrate is necessary because mostmetals are more volatile in thechlorinated form. Thus, for example,more low volatile metals may report tothe combustion gas as a vapor thanwould be otherwise be entrained in thecombustion gas absent the presence ofchlorine. In addition, the vapor form ofthe metal is more difficult to control.Although most semivolatile and lowvolatile metal species are in theparticulate phase at gas temperatures atthe inlet to the particulate mattercontrol device, semivolatile metals thatcondense from the vapor phase partitionto smaller particulates and are moredifficult to control than low volatilemetals that are emitted in the form ofentrained, larger particulates.

To establish and comply with thefeedrate limit, you must sample andanalyze, and continuously monitor theflowrate, of all feedstreams (includinghazardous waste, raw materials, andother fuels and additives) except naturalgas, process air, and feedstreams fromvapor recovery systems for totalchlorine content. As proposed, youmust establish a maximum 12-hourrolling average feedrate limit based onoperations during the comprehensiveperformance test as the average of thetest run averages.

Commenters suggest that chlorinefeedrate limits are not needed forsources with semivolatile and lowvolatile metal feedrates, when expressedas maximum theoretical emissionconcentrations, less than the emissionstandard. We agree. In this situation,you would be eligible for the waiver ofperformance test under § 63.1207(m).The requirements of that provision (e.g.,monitor and record metals feedrates andgas flowrates to ensure that metalsfeedrate, expressed as a maximumtheoretical emission concentration, doesnot exceed the emission standard) applyin lieu of the operating parameter limitsbased on performance testing discussed

above. We note, however, that youwould still need to establish amaximum feedrate limit for totalchlorine as an operating parameter limitfor the hydrochloric acid/chlorine gasemission standard (discussed below),unless you also qualified for a waiver ofthat emission standard under§ 63.1207(m).

4. What Are the MonitoringRequirements for Carbon Monoxide andHydrocarbon?

You must maintain compliance withthe carbon monoxide and hydrocarbonemission standards using continuousemissions monitoring systems (CEMS).In addition, you must use an oxygenCEMS to correct continuously thecarbon monoxide and hydrocarbonlevels recorded by their CEMS to 7percent oxygen.

As proposed, the averaging period forcarbon monoxide and hydrocarbonCEMS is a one-hour rolling averageupdated each minute. This is consistentwith current RCRA requirements andcommenters did not recommend analternative averaging period.

We also are promulgatingperformance specifications for carbonmonoxide, hydrocarbon, and oxygenCEMS. The carbon monoxide andoxygen CEMS performancespecifications are codified asPerformance Specification 4B inappendix B, part 60. This performancespecification is the same as thespecification currently used for BIFs inappendix IX, part 266. It also is verysimilar to existing appendix B, part 60Performance Specifications 3 (foroxygen) and 4A (for carbon monoxide).New specification 4B references manyof the provisions of Specifications 3 and4A.

The hydrocarbon CEMS performancespecification is codified as PerformanceSpecification 8A in appendix B, part 60.This specification is also identical to thespecification currently used for BIFs insection 2.2 of appendix IX, part 266,with one exception. We deleted thequality assurance section and placed itin the appendix to subpart EEE of part63 promulgated today to be consistentwith our approach to part 60performance specifications.

We discuss below several issuespertaining to monitoring with theseCEMS: (1) The requirement to establishsite-specific alternative span values insome situations; (2) consequences ofexceeding the span value of the CEMS;and (3) the need to adjust the oxygencorrection factor during startup andshutdown.

a. When Are You Required toEstablish Site-Specific Alternative Span



Values? As proposed, if you normallyoperate at an oxygen correction factor ofmore than 2 (e.g., a cement kilnmonitoring carbon monoxide in the by-pass duct), you must use a carbonmonoxide or hydrocarbon CEMS with aspan proportionately lower than thevalues prescribed in the performancespecifications relative to the oxygencorrection factor at the CEMS samplingpoint. See the appendix to Subpart EEE,part 63: Quality Assurance Proceduresfor Continuous Emissions MonitorsUsed for Hazardous Waste Combustors.

This requirement arose from ourexperience with implementing the BIFrule when we determined that theprescribed span values for the carbonmonoxide and hydrocarbon CEMS maylead to high error in corrected emissionvalues due to the effects of making theoxygen correction. For example, acement kiln may analyze for carbonmonoxide emissions in the by-pass ductwith oxygen correction factors on theorder of 10. At the low range of thecarbon monoxide CEMS span—200 ppmas prescribed by PerformanceSpecification 4B—with an acceptablecalibration drift of three percent, anerror of 6 ppm is the result. Accountingfor the oxygen correction factor of 10,however, drives the error in themeasurement due to calibration drift upto 60 ppm. This is more than half thecarbon monoxide emission standard of100 ppm and is not acceptable. Atcarbon monoxide readings close to the100 ppm standard, true carbonmonoxide levels may be well above orwell below the standard.

Consider the same example undertoday’s requirement. For an oxygencorrection factor of 10, the low rangespan for the carbon monoxide CEMSmust be 200 divided by 10, or 20 ppm.The allowable calibration drift of threepercent of the span allows an error of0.6 ppm at 20 ppm. Applying an oxygencorrection factor of 10 results in anabsolute calibration drift error of 6ppmat an oxygen-corrected carbon monoxidereading of 200.

b. What Are the Consequences ofExceeding the Span Value for CarbonMonoxide and Hydrocarbon CEMS? Ifyou do not elect to use a carbonmonoxide CEMS with a higher spanvalue of 10,000 ppmv and ahydrocarbon CEMS with a higher spanvalue of 500 ppmv, you must configureyour CEMS so that a one-minute carbonmonoxide value reported as 3,000 ppmvor greater must be recorded (and used tocalculate the hourly rolling average) as10,000 ppmv, and a one-minutehydrocarbon value reported as 200ppmv or greater must be recorded as 500ppmv.

If you elect to use a carbon monoxideCEMS with a span range of 0–10,000ppmv, you must use one or more carbonmonoxide CEMS that meet thePerformance Specification 4B for threeranges: 0–200 ppmv; 1–3,000 ppmv; and0–10,000 ppmv. Specification 4Bprovides requirements for the first tworanges. For the (optional) high range of0–10,000 ppmv, the CEMS must alsocomply with Performance Specification4B, except that the calibration drift mustbe less than 300 ppmv and calibrationerror must be less than 500 ppmv. Thesevalues are based on the allowable driftand error, expressed as a percentage ofspan, that the specification requires forthe two lower span levels.

If you elect to use a hydrocarbonCEMS with a span range of 0–500 ppmv,you must use one or more hydrocarbonCEMS that meet PerformanceSpecification 8A for two ranges: 0–100ppmv, and 0–500 ppmv. Specification8A provides requirements for the firstrange. For the (optional) high range of0–500 ppmv, the CEMS must alsocomply with Performance Specification8A, except: (1) The zero and high-leveldaily calibration gas must be between 0and 100 ppmv and between 250 and 450ppmv, respectively; (2) the strip chartrecorder, computer, or digital recordermust be capable of recording allreadings within the CEMS measurementrange and must have a resolution of 2.5ppmv; (3) the CEMS calibration mustnot differ by more than ±15 ppmv aftereach 24 hour period of the seven daytest at both zero and high levels; (4) thecalibration error must be no greater than25 ppmv; and (5) the zero level, mid-level, and high level values used todetermine calibration error must be inthe range of 0–200 ppmv, 150–200ppmv, and 350–400 ppmv, respectively.These requirements for the optionalhigh range (0–500 ppmv) are derivedproportionately from the requirementsin Specification 8A for the lower range(0–100 ppmv).

The rule provides this requirementbecause we are concerned that, whencarbon monoxide and hydrocarbonmonitors record a one-minute value atthe upper span level, the actual level ofcarbon monoxide or hydrocarbons maybe much higher (i.e., these CEMS often‘‘peg-out’’ at the upper span level). Thishas two inappropriate consequences.First, the source may actually beexceeding the carbon monoxide orhydrocarbon standard even though theCEMS indicates that it is not. Second, ifthe carbon monoxide or hydrocarbonhourly rolling average were to exceedthe standard, triggering an automaticwaste feed cutoff, the emission levelmay drop back below the standard

much sooner than it otherwise would ifthe actual one-minute average emissionlevels were recorded (i.e., rather thanone-minute averages pegged at theupper span value). Thus, thisdiminishes the economic disincentivefor incurring automatic waste feedcutoffs of not being able to restart thehazardous waste feed until carbonmonoxide and hydrocarbon levels arebelow the standard.

We considered applying these ‘‘out-of-span’’ requirements when anyrecorded value (i.e., any value recordedby the CEMS on a frequency of at leastevery 15 seconds), rather than one-minute average values, exceeded theupper span level. Commenters pointout, however, that CEMS mayexperience short-term electronicglitches that cause the monitored outputto spike for a very short time period. Weconcur, and conclude that we should beconcerned only about one-minuteaverage values because these short-termelectronic glitches (that are not causedby emission excursions) could result inan undesirable increase in automaticwaste feed cutoffs.

You may prefer to use carbonmonoxide or hydrocarbon CEMS thathave upper span values between 3,000and 10,000 ppmv and between 100 and500 ppmv, respectively. If you believethat you would not have one-minuteaverage carbon monoxide orhydrocarbon levels as high as 10,000ppmv and 500 ppmv, respectively, youmay determine that it would be lessexpensive to use monitors with lowerupper span levels (e.g., you may be ableto use a single carbon monoxide CEMSto meet performance specifications forall three spans—the two lower spansrequired by Specification 4B, and ahigher span (but less than 10,000)). Youmust still record, however, any one-minute average carbon monoxide orhydrocarbon levels that are at or abovethe span as 10,000 ppmv and 500 ppmv,respectively.

c. How Is the Oxygen CorrectionFactor Adjusted during Startup andShutdown? You must identify in yourStartup Shutdown, and MalfunctionPlan a projected oxygen correctionfactor to use during periods of startupand shutdown. The projected oxygencorrection factor should be based onnormal operations. See§ 63.1206(c)(2)(iii). The rule providesthis requirement because the oxygenconcentration in the combustor canexceed 15% during startup andshutdown, causing the correction factorto increase exponentially from thenormal value. Such large correctionfactors result in corrected carbon



monoxide and hydrocarbon levels thatare inappropriately inflated.

5. What Are the Operating ParameterLimits for Hydrochloric Acid/ChlorineGas?

You must maintain compliance withthe hydrochloric acid/chlorine gas

emission standard by establishing andcomplying with limits on operatingparameters. See § 63.1209(o). Thefollowing table summarizes theseoperating parameter limits. All sourcesmust comply with the maximumchlorine feedrate limit. Other operating

parameter limits apply depending onthe type of hydrochloric acid/chlorinegas emission control device you use.

BILLING CODE 6560–50–P






244 See discussion in Section VII.D.3 above in thetext for the rationale for exempting thesefeedstreams for monitoring for chlorine content.

Hydrochloric acid/chlorine gasemissions from hazardous wastecombustors are controlled by controllingthe feedrate of total chlorine (organicand inorganic) and either wet or dryscrubbers. We discuss below theoperating parameter limits that apply toeach control technique.

a. Maximum Chlorine Feedrate Limit.As proposed, you must establish a limiton the maximum feedrate of chlorine,both organic and inorganic, from allfeedstreams based on levels fed duringthe comprehensive performance test.Chlorine feedrate is an importantemission control technique because theamount of chlorine fed into a combustordirectly affects emissions ofhydrochloric acid/chlorine gas. Toestablish and comply with the feedratelimit, you must sample and analyze, andcontinuously monitor the flowrate, of allfeedstreams (including hazardous waste,raw materials, and other fuels andadditives) except natural gas, processair, and feedstreams from vaporrecovery systems for chlorine content.244

Also as proposed, you must establish amaximum 12-hour rolling averagefeedrate limit based on operationsduring the comprehensive performancetest as the average of the test runaverages.

One commenter states that a chlorinefeedrate is not necessary for cementkilns because cement kilns have aninherent incentive to control chlorinefeedrates: to avoid operational problemssuch as the formation of material ringsin the kiln or alkali-chloridecondensation on the walls. Although weunderstand that cement kilns mustmonitor chlorine feedrates foroperational reasons, several cementkilns in our data base emit levels ofhydrochloric acid/chlorine gas at levelsabove today’s emissions standard. Weconclude, therefore, that the operationalincentive to limit chlorine feedrates isnot adequate to ensure compliance withthe hydrochloric acid/chlorine gasemission standard.

b. Wet Scrubbers. If your combustor isequipped with a wet scrubber, you mustestablish, continuously monitor, andcomply with limits on the followingoperating parameters:

i. Maximum Flue Gas Flowrate orKiln Production Rate. As proposed, youmust establish a limit on maximum fluegas flowrate or kiln production rate asa surrogate. See 61 FR at 17433. Gasflowrate is a key parameter affecting thecontrol efficiency of a wet scrubber (andany emissions control device). As gas

flowrate increases, control efficiencygenerally decreases unless otheroperating parameters are adjusted toaccommodate the increased flowrate.Cement kilns and lightweight aggregatekilns may establish a limit on maximumproduction rate (e.g., raw materialfeedrate or clinker or aggregateproduction rate) in lieu of a maximumgas flowrate given that production ratedirectly relates to flue gas flowrate.

As proposed, you must establish amaximum gas flowrate or productionrate limit as the average of themaximum hourly rolling averages foreach run of the comprehensiveperformance test.

We did not receive adverse commenton this compliance parameter.

ii. Minimum Pressure Drop Across theScrubber. You must establish a limit onminimum pressure drop across thescrubber. If your combustor is equippedwith a high energy scrubber (e.g.,venturi, calvert), you must establish anhourly rolling average limits based onoperations during the comprehensiveperformance test. The hourly rollingaverage is established as the average ofthe test run averages.

If your combustor is equipped with alow energy scrubber (e.g., spray tower),you must establish a limit on minimumpressure drop based on themanufacturer’s specification. You mustcomply with the limit on an hourlyrolling average basis.

Pressure drop across a wet scrubber isan important operating parameterbecause it is an indicator of good mixingof the two fluids, the scrubber liquidand the flue gas. A low pressure dropindicates poor mixing and, hence, poorefficiency. A high pressure dropindicates good removal efficiency.

One commenter states that wetscrubber pressure drop is not animportant parameter for packed-bed,low energy wet scrubbers. Thecommenter states that the performanceof a packed-bed scrubber is based ongood liquid-to-gas contacting. Thus,performance is dependent on packingdesign and scrubber fluid flow. Inaddition, the commenter states thatscrubber liquid flow rate (andrecirculation rate and make-up waterflow rate) are adequate for assuringproper scrubber operation. We note thatfor many types of low energy wetscrubbers, pressure drop can be a roughindicator of scrubber liquid and flue gascontacting. Thus, although it is not acritical parameter, the minimumpressure drop of a low energy scrubbershould still be monitored and compliedwith on a continuous basis.

Because pressure drop for a lowenergy scrubber (e.g., spray towers,

packed beds, or tray towers) is not asimportant as for a high energy scrubberto maintain performance, however, therule requires you to establish a limit onthe minimum pressure drop for a lowenergy scrubber based on manufacturerspecifications, rather than levelsdemonstrated during compliancetesting. You must comply with this limiton an hourly rolling average basis. Thepressure drop for high energy wetscrubbers, such as venturi or calvertscrubbers, however, is a key operatingparameter to ensure the scrubbermaintains performance. Accordingly,you must base the minimum pressuredrop for these devices on levelsachieved during the comprehensive test,and you must establish an hourly rollingaverage limit.

iii. Minimum Liquid Feed Pressure.You must establish a limit on minimumliquid feed pressure to a low energyscrubber. The limit must be based onmanufacturer’s specifications and youmust comply with it on an hourlyrolling average basis.

The rule requires a limit on liquidfeed pressure because the removalefficiency of a low energy wet scrubbercan be directly affected by theatomization efficiency of the scrubber. Adrop in liquid feed pressure may be anindicator of poor atomization and poorscrubber removal efficiency. We are notrequiring a limit on minimum liquidfeed pressure for high energy scrubbersbecause liquid flow rate rather than feedpressure is the dominant operatingparameter for high energy scrubbers.

We acknowledge, however, that notall wet scrubbers rely on atomizationefficiency to maintain performance. Ifmanufacturer’s specifications indicatethat atomization efficiency is not animportant parameter that controls theefficiency of your scrubber, you maypetition permitting officials under§ 63.1209(g)(1) to waive this operatingparameter limit.

iv. Minimum Liquid pH. You mustestablish dual ten-minute and hourlyrolling average limits on minimum pHof the scrubber water based onoperations during the comprehensiveperformance test. The hourly rollingaverage is established as the average ofthe test run averages.

The pH of the scrubber liquid is animportant operating parameter because,at low pH, the scrubber solution is moreacidic and removal efficiency ofhydrochloric acid and chlorine gasdecreases.

These requirements, except for theproposed ten-minute averaging period,are the same as we proposed. See 61 FRat 17433. We did not receive adversecomments.



245 In fact, complying with limits on liquidflowrate and gas flowrate, rather than complyingwith a liquid flowrate/gas flowrate ratio, is a moreconservative approach to ensure that theperformance test ratio is maintained (at aminimum). Thus, we prefer that you establish alimit on liquid flowrate (in conjunction with thelimit gas flowrate) in lieu of a limit on the ratio.

246 We note that sorbent should be fed to a dryscrubber in excess of the stoichiometricrequirements for neutralizing the anion componentin the flue gas. Lower levels of sorbent, even abovestoichiometric requirements, would limit theremoval of acid gasses.

247 We note that flowrate measurement devicesare available for ten-minute average times (e.g.,those based on volumetric screw feeders whichprovide instantaneous measurements).

v. Minimum Scrubber LiquidFlowrate or Minimum Liquid/Gas Ratio.You must establish an hourly rollingaverage limits on either minimumscrubber liquid flowrate and maximumflue gas flowrate or minimum liquid/gasratio based on operations during thecomprehensive performance test. Thehourly rolling average is established asthe average of the test run averages.

Liquid flowrate and flue gas flowrateor liquid/gas ratio are importantoperating parameters because a highliquid-to-gas-flowrate ratio is indicativeof good removal efficiency.

We had proposed to limit the liquid-to-gas ratio only. Commenters suggestthat a limit on liquid-to-gas flow ratiowould not be needed if the liquidflowrate and flue gas flowrate werelimited instead. They reason that,because gas flowrate is already limited,limiting liquid flowrate as well wouldensure that the liquid-to-gas ratio ismaintained. We agree. During normaloperations, the liquid flowrate can onlybe higher than levels during theperformance test, and gas flowrate canonly be lower than during theperformance test. Thus, the numeratorin the liquid flowrate/gas flowrate ratiocould only be larger, and thedenominator could only be smaller.Consequently, the liquid flowrate/gasflowrate during normal operations willalways be higher than during thecomprehensive performance test.Consequently, we agree that a limit onliquid-to-gas-ratio is not needed if youestablish a limit on liquid flowrate andflue gas flowrate. Establishing limits onthese parameters is adequate to ensurethat the liquid flowrate/gas ratio ismaintained.245

c. Dry Scrubbers. A dry scrubberremoves hydrochloric acid from the fluegas by adsorbing the hydrochloric acidonto sorbent, normally an alkalinesubstance like limestone. As proposed,if your combustor is equipped with adry scrubber, you must establish,continuously monitor, and comply withlimits on the following operatingparameters: Gas flowrate or kilnproduction rate; sorbent feedrate; carrierfluid flowrate or nozzle pressure drop;and sorbent specifications. See 61 FR at17434.

i. Maximum Flue Gas Flowrate orKiln Production Rate. As proposed, youmust establish a limit on maximum flue

gas flowrate or kiln production rate asa surrogate. The limit is established andmonitored as discussed above for wetscrubbers.

ii. Minimum Sorbent Feedrate. Youmust establish an hourly rolling averagelimit on minimum sorbent feedratebased on feedrate levels during thecomprehensive performance test. Thehourly rolling average is established asthe average of the test run averages.

Sorbent feedrate is important because,as more sorbent is fed into the dryscrubber, removal efficiency ofhydrochloric acid and chlorine gasincreases.246 Conversely, lower sorbentfeedrates tend to cause removalefficiency to decrease.

At proposal, we invited comment onwhether a ten-minute rolling average isappropriate for sorbent feedrate (61 FRat 17434). We were concerned that somefacilities may not automate their dryscrubbers to add sorbent solutions butinstead add batches of virgin sorbentsolution. Thus, we were concerned thata ten-minute rolling average may not bepracticable in all cases. Somecommenters are concerned that a ten-minute limit would be difficult tomeasure, especially in the case of batchaddition of sorbent. Nonetheless, wehave determined upon reanalysis thatsorbent is not injected into the flue gasin ‘‘batches.’’ Although sorbent may beadded in batches to storage or mixingvessels, it must be injected into the fluegas continuously to provide continuousand effective removal of acid gases.Thus, ten-minute rolling average limitswould be practicable and appropriatefor sorbent injection feedrates if ten-minute averages were required in thisfinal rule.247 However, as discussed inPart Five, Section VII.B, we havedecided to not require ten-minuteaveraging periods on a national basis.Permitting officials may, however,determine that shorter averaging periodsare needed to better assure compliancewith the emission standard.

iii. Minimum Carrier Fluid Flowrateor Nozzle Pressure Drop. A carrier fluid,normally air or water, is necessary totransport and inject the sorbent into thegas stream. As proposed, you mustestablish and continuously monitor alimit on either minimum carrier gas orwater flowrate or pressure drop across

the nozzle to ensure that the flow anddispersion of the injected sorbent intothe flue gas stream is maintained. Youmust base the limit on manufacturer’sspecifications, and comply with thelimit on a one-hour rolling averagebasis.

Without proper carrier flow to the dryscrubber, the sorbent flow into thescrubber will decrease causing theefficiency to decrease. Nozzle pressuredrop is also an indicator of carrier gasflow into the scrubber. At higherpressure drops, more sorbent is carriedto the dry scrubber.

iv. Identification of Sorbent Brandand Type or Adsorption Properties. Youmust either identify the sorbent brandand type used during thecomprehensive performance test andcontinue using that sorbent, or identifythe adsorption properties of that sorbentand use a sorbent having equivalent orbetter properties. This will ensure thatthe sorbent’s adsorption properties aremaintained.

We proposed to require sources tocontinue to use the same sorbent brandand type as they used during thecomprehensive performance test orobtain a waiver from this requirementfrom the Administrator. See 61 FR at17434. As discussed above in thecontext of specifying the brand ofcarbon used in carbon injection systemsto control dioxin/furan, we havedetermined that sources should have theoption of using manufacturer’sspecifications to specify the sorptionproperties of the sorbent used duringthe comprehensive performance test.You may use sorbent of other brands ortypes provided that it has equivalent orbetter sorption properties. You mustinclude in the operating record writtendocumentation that the substitutesorbent will provide the same level ofcontrol as the original sorbent.

6. What Are the Operating ParameterLimits for Particulate Matter?

You must maintain compliance withthe particulate matter emission standardby establishing and complying withlimits on operating parameters. See§ 63.1209(m). The following tablesummarizes these operating parameterlimits. All incinerators must complywith the limit on maximum ashfeedrate. Other operating parameterlimits apply depending on the type ofparticulate matter control device youuse.

BILLING CODE 6560–50–P






248 See discussion in Section VII.D.3 above in thetext for the rationale for exempting thesefeedstreams from monitoring for ash content.

Particulate matter emissions fromhazardous waste combustors arecontrolled by controlling the feedrate ofash to incinerators and using aparticulate matter control device. Wediscuss below the operating parameterlimits that apply to each controltechnique.

a. Maximum Ash Feedrate. Asproposed, if you own or operate anincinerator, you must establish a limiton the maximum feedrate of ash from allfeedstreams based on the levels fedduring the comprehensive performancetest. To establish and comply with thefeedrate limit, you must sample andanalyze, and continuously monitor theflowrate of all feedstreams (includinghazardous waste, and other fuels andadditives) except natural gas, processair, and feedstreams from vaporrecovery systems for ash content.248

Also as proposed, you must establish amaximum 12-hour rolling averagefeedrate limit based on operationsduring the comprehensive performancetest as the average of the test runaverages. See 61 FR at 17438.

Ash feedrate for incinerators is animportant particulate matter controlparameter because ash feedrates canrelate directly to emissions ofparticulate matter (i.e., ash contributesto particulate matter in flue gas). We arenot requiring an ash feedrate limit forcement or lightweight aggregate kilnsbecause particulate matter from thosecombustors is dominated by rawmaterials entrained in the flue gas. Thecontribution to particulate matter of ashfrom hazardous waste or otherfeedstreams is not significant. Wediscussed this issue at proposal.

A commenter states that ash feedratelimits are not needed for combustorsusing fabric filters, suggesting that fabricfilter pressure drop and opacitymonitoring are sufficient for complianceassurance. We discuss previously in thissection (i.e., Part Five, Section VII) ourconcern that neither opacity monitors,nor limits on control device operatingparameter, nor limits on the feedrates ofconstituents that can contribute directlyto emissions of hazardous air pollutantscomprise an ideal compliance assuranceregime. We would prefer the use of aparticulate matter CEMS for complianceassurance but cannot achieve that goalat this time. Absent the use of a CEMSand given the limitations of theindividual compliance tools currentlyavailable, we are reluctant to forgo on anational, generic basis requiring limitson an operating parameter such as ash

feedrate that we know can relatedirectly to particulate emissions.However, you may petition permittingofficials under § 63.1209(g)(1) forapproval to waive the ash feedrate limitbased on data or informationdocumenting that pressure drop acrossthe fabric filter coupled with an opacitymonitor would provide equivalent orbetter compliance assurance than a limiton ash feedrate.

b. Wet Scrubbers. As proposed, ifyour combustor is equipped with a wetscrubber, you must establish,continuously monitor, and comply withlimits on the operating parametersdiscussed below. High energy wetscrubbers (e.g., venturi, calvert) removeparticulate matter by capturing particlesin liquid droplets and separating thedroplets from the gas stream. Ionizingwet scrubbers use both an electricalcharge and wet scrubbing to removeparticulate matter. Low energy wetscrubbers that are not ionizing wetscrubbers (e.g., packed bed, spray tower)are only subject to the scrubber watersolids content operating parameterrequirements for particulate mattercontrol because they are primarily usedto control emissions of acid gases andonly provide incidental particulatematter control.

i. Maximum Flue Gas Flowrate orKiln Production Rate. For high energyand ionic wet scrubbers, you mustestablish a limit on maximum flue gasflowrate or kiln production rate as asurrogate. See 61 FR at 17438. Gasflowrate is a key parameter affecting thecontrol efficiency of a wet scrubber (andany emissions control device). As gasflowrate increases, control efficiencygenerally decreases unless otheroperating parameters are adjusted toaccommodate the increased flowrate.Cement kilns and lightweight aggregatekilns may establish a limit on maximumproduction rate (e.g., raw materialfeedrate or clinker or aggregateproduction rate) in lieu of a maximumgas flowrate given that production ratedirectly relates to flue gas flowrate.


ii. Minimum Pressure Drop Across theScrubber. For high energy scrubbersonly, you must establish an hourlyrolling average limits on minimumpressure drop across the scrubber basedon operations during the comprehensiveperformance test. The hourly rollingaverage is established as the average ofthe test run averages. See the discussionin Section VII.D.5.b above for a

discussion on the approach forcalculating limits from comprehensiveperformance test data.

iii. Minimum Scrubber LiquidFlowrate or Minimum Liquid/Gas Ratio.For high energy wet scrubbers, you mustestablish an hourly rolling averagelimits on either minimum scrubberliquid flowrate and maximum flue gasflowrate or minimum liquid/gas ratiobased on operations during thecomprehensive performance test. Thehourly rolling average is established asthe average of the test run averages. Seethe discussion in Section VII.D.5.babove for a discussion on the approachfor calculating limits fromcomprehensive performance test data.

iv. Maximum Solids Content ofScrubber Water or Minimum BlowdownRate Plus Minimum Scrubber TankVolume or Level. For all wet scrubbers,to maintain the solids content of thescrubber water to levels no higher thanduring the comprehensive performancetest, you must establish a limit oneither: (1) Maximum solids content ofthe scrubber water; or (2) minimumblowdown rate plus minimum scrubbertank volume or level. If you elect toestablish a limit on maximum solidscontent of the scrubber water, you mustcomply with the limit either by: (1)Continuously monitoring the solidscontent and establishing 12-hour rollingaverage limits based on solids contentduring the comprehensive performancetest; or (2) periodic manual samplingand analysis of scrubber water for solidscontent. Under option 1, the 12-hourrolling average is established as theaverage of the test run averages. Underoption 2, you must either comply witha default sampling and analysisfrequency for scrubber water solidscontent of once per hour or recommendan alternative frequency in yourcomprehensive performance test planthat you submit for review andapproval.

Solids content in the scrubber wateris an important operating parameterbecause as the solids content increases,particulate emissions increase. This isattributable to evaporation of scrubberwater and release of previously capturedparticulate back into the flue gas.Blowdown is the amount of scrubberliquid removed from the process andnot recycled back into the wet scrubber.As scrubber liquid is removed and notrecycled, solids are removed. Thus,blowdown is an operating parameterthat affects solids content and can beused as a surrogate for measuring solidscontent directly. See 61 FR 17438.

The proposed rule would haverequired continuously monitored limitson either minimum blowdown or a



maximum solids content. In response tocomments and upon reanalysis of theissues, we conclude that we need tomake two revisions to theserequirements. First, we are concernedthat it may be problematic tocontinuously monitor the solids contentof scrubber water. Consequently, werevised the requirements to allowmanual sampling and analysis on anhourly basis, unless you justify analternative frequency. Second, we areconcerned that a limit on blowdownrate without an associated limit oneither minimum scrubber water tankvolume or level would not be adequateto provide control of solids content. Thesolids concentration in blowdown tankscould be higher at lower water levels.Therefore, water levels need to be atleast equivalent to the levels during thecomprehensive performance test. Thisshould not be a significant additionalburden. Sources should be monitoringthe water level in the scrubber watertank as a measure of good operatingpractices. Consequently, we revise therequirement to require a minimum tankvolume or level in conjunction with aminimum blowdown rate for sourcesthat elect to use that compliance option.

c. Fabric Filter. If your combustor isequipped with a fabric filter, you mustestablish, continuously monitor, andcomply with limits on the operatingparameters discussed below.

i. Maximum Flue Gas Flowrate orKiln Production Rate. As proposed, youmust establish a limit on maximum fluegas flowrate or kiln production rate asa surrogate. Gas flowrate is a keyparameter affecting the controlefficiency of a fabric filter (and anyemissions control device). As gasflowrate increases, control efficiencygenerally decreases unless otheroperating parameters are adjusted toaccommodate the increased flowrate.Cement kilns and lightweight aggregatekilns may establish a limit on maximumproduction rate (e.g., raw materialfeedrate or clinker or aggregateproduction rate) in lieu of a maximumgas flowrate given that production ratedirectly relates to flue gas flowrate.


ii. Minimum Pressure Drop andMaximum Pressure Drop Across theFabric Filter. You must establish a limiton minimum pressure drop andmaximum pressure drop across eachcell of the fabric filter based onmanufacturer’s specifications.

Filter failure is typically due to filterholes, bleed-through migration ofparticulate through the filter and cake,and small ‘‘pin holes’’ in the filter andcake. Because low pressure drop is anindicator of one of these types of failure,pressure drop across the fabric filter isan indicator of fabric filter failure.

We had proposed to establish limitson minimum pressure drop based on theperformance test. Commenters indicate,however, that maintaining a pressuredrop not less than levels during theperformance test will not ensurebaghouse performance. We concur. Thepressure change caused by fabric holesmay not be measurable, especially atlarge sources with multiple chamberfilter housing units that operate inparallel. In addition, operating at highpressure drop may not be desirablebecause high pressures can create pinholes.

Nonetheless, establishing a limit onminimum pressure drop based onmanufacturer’s recommendations, assuggested by a commenter, is areasonable and prudent approach tohelp ensure fabric filter performance.We have since determined that anoperating parameter limit for maximumpressure drop across each cell of thefabric filter, based on manufacturerspecifications, is also necessary. Asdiscussed above, a high pressure drop ina cell of a fabric filter may cause smallpinholes to form or may be indicative ofbag blinding or plugging, which couldresult in increased particulateemissions. We do not consider thisadditional provision to be burdensome,especially because both the maximumand minimum pressure drop limits arebased on manufacturer specifications onan hourly rolling average. Thesepressure drop monitoring requirements,in combination with COMS for cementkilns and bag leak detection systems forincinerators and lightweight aggregatekilns, provide a significant measure ofassurance that control performance ismaintained.

d. Electrostatic Precipitators andIonizing Wet Scrubbers. As proposed, ifyour combustor is equipped with anelectrostatic precipitator or ionizing wetscrubber, you must establish,continuously monitor, and comply withlimits on the operating parametersdiscussed below.

i. Maximum Flue Gas Flowrate orKiln Production Rate. You mustestablish a limit on maximum flue gasflowrate or kiln production rate as asurrogate. Gas flowrate is a keyparameter affecting the controlefficiency of an emissions controldevice. As gas flowrate increases,control efficiency generally decreases

unless other operating parameters areadjusted to accommodate the increasedflowrate. Cement kilns and lightweightaggregate kilns may establish a limit onmaximum production rate (e.g., rawmaterial feedrate or clinker or aggregateproduction rate) in lieu of a maximumgas flowrate given that production ratedirectly relates to flue gas flowrate.


ii. Minimum Secondary Power Inputto Each Field. You must establish anhourly rolling average limit onminimum secondary power (kVA) inputto each field of the electrostaticprecipitator or ionizing wet scrubberbased on operations during thecomprehensive performance test. Thehourly rolling average is established asthe average of the test run averages.

Electrostatic precipitators captureparticulate matter by charging theparticulate in an electric field andcollecting the charged particulate on aninversely charged collection plate.Higher voltages improve magnetic fieldstrength, resulting in charged particlemigration to the collection plate. Highcurrent leads to an increased particlecharging rate and increased electric fieldstrength near the collection electrode,increasing collection at the plate, aswell. Therefore, maximizing bothvoltage and current by specifyingminimum power input to theelectrostatic precipitator is desirable forgood particulate matter collection inelectrostatic precipitators. For thesereasons, the rule requires you to monitorpower input to each field of theelectrostatic precipitator to ensure thatcollection efficiency is maintained atperformance test levels.

Power input to an ionizing wetscrubber is important because it directlyaffects particulate removal. Ionizing wetscrubbers charge the particulate prior toit entering a packed bed wet scrubber.The charging aids in the collection ofthe particulate onto the packing surfacein the bed. The particulate is thenwashed off the packing by the scrubberliquid. Therefore, power input is a keyparameter to proper operation of anionizing wet scrubber.

One commenter suggests that aminimum limit on electrostaticprecipitator voltage be used instead ofpower input because, at low particulatematter loadings, operation at maximumpower input is inefficient. Anothercommenter suggests that neither a limiton voltage or power input is appropriatebecause a minimum limit would

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249 You are required to establish operatingrequirements only for hazardous waste firingsystems because of DRE standard applies only tohazardous waste. Permitting officials maydetermine on a site-specific basis under authorityof § 63.1209(g)(2), however, that combustion ofother fuels or wastes may affect your ability tomaintain DRE for hazardous waste. Accordingly,permitting officials may define operatingrequirements for other (i.e., other than hazardouswaste) waste or fuel firing systems. Permittingofficials may also determine under that provisionon a site-specific basis that operating requirementsother than those prescribed for DRE (and goodcombustion practices) may be needed to ensurecompliance with the DRE standard.

actually cause a potential decrease inoperational efficiency (required powerinput and voltage are strong functions ofgas and particulate characteristics,electrostatic precipitator arcing andsparking at high voltage and powerrequirements, etc.). Alternatively, theyrecommend that a limit on theminimum number of energizedelectrostatic precipitator fields beestablished. We continue to maintainthat a minimum limit on power input toeach field of the electrostaticprecipitator is generally accepted as anappropriate parameter for assuringelectrostatic precipitator performance.Consequently, it is an appropriateparameter for a generic, nationalstandard. If you believe, however, thatin your situation limits on alternativeoperating parameters may better assurethat control performance is maintainedyou may request approval to usealternative monitoring approachesunder § 63.1209(1).

Another commenter suggests that, inaddition to a minimum power input foran ionizing wet scrubber, a limit shouldbe set on the maximum time allowableto be below the minimum voltage.While feasible, we conclude that thislimit is not necessary on a national basisbecause the one hour rolling averagerequirement limits the amount of time asource can operate below its minimumvoltage limit. We acknowledge,however, that a permit writer may findit necessary to require shorter averagingperiods (e.g., ten-minute orinstantaneous limits) to better controlthe amount of time a source can operateat levels below its limit.

7. What Are the Operating ParameterLimits for Destruction and RemovalEfficiency?

You must establish, monitor, andcomply with the same operatingparameter limits to ensure compliancewith the destruction and removalefficiency (DRE) standard as youestablish to ensure good combustionpractices are maintained for compliancewith the dioxin/furan emissionstandard. See § 63.1209(j) and thediscussion in Section VII.D.1 above.This is because compliance with theDRE standard is ensured by maintainingcombustion efficiency using goodcombustion practices. Thus, the DREoperating parameters are: maximumwaste feedrate for pumpable andnonpumpable wastes, minimum gastemperature for each combustionchamber, maximum gas flowrate or kilnproduction rate, and parameters thatyou recommend to ensure the

operations of each hazardous wastefiring system are maintained.249

VIII. Which Methods Should Be Used forManual Stack Tests and FeedstreamSampling and Analysis?

This part discusses the manual stacktest and the feedstream sampling andanalysis methods required by today’srule.

A. Manual Stack Sampling TestMethods

To demonstrate compliance withtoday’s rule, you must use: (1) Method0023A for dioxin and furans; (2) Method29 for mercury, semivolatile metals, andlow volatile metals; (3) Method 26A forhydrochloric acid and chlorine; and (4)Method 5 or 5i for particulate matter.These methods are found at 40 CFR part60, appendix A, and in ‘‘Test Methodsfor Evaluating Solid Waste, Physical/Chemical Methods,’’ EPA publication.

In the NPRM, we proposed that BIFmanual stack test methods currentlylocated in SW–846 be required todemonstrate compliance with theproposed standards. Based on publiccomments from the proposal, in theDecember 1997 NODA we consideredsimply citing the ‘‘Air Methods’’ foundin appendix A to part 60. Our rationalewas that facilities may be required toperform two identical tests, one fromSW–846 for compliance with MACT orRCRA and one from part 60, appendixA, for compliance with other air rulesusing identical test methods simplybecause one method is an SW–846method and the other an Air Method.See 62 FR at 67803. To facilitatecompliance with all air emissions stacktests, we stated that we would list themethods found in 40 CFR part 60,appendix A, as the stack test methodsused to comply with the standards.Later in this section we present anexception for dioxin and furan testing.

In today’s rule, we adopt the approachof the December 1997 NODA andrequire that the test methods found in40 CFR part 60, appendix A be used todemonstrate compliance with theemission standards of today’s rule,

except for dioxin and furan.Specifically, today’s rule requires you touse Method 0023A in SW–846 forsampling dioxins and furans from stackemissions. As noted by commenters,improvements have been made to thedioxin and furan Method 0023A in theThird Update of SW–846 that have beenpreviously incorporated into today’sregulations. See the 40 CFR 63.1208(a),incorporation of SW–846 by reference.However, these have not yet beenincorporated into 40 CFR part 60,Appendix A. To capture theseimprovements to the method, today’srule incorporates by reference SW–846Method 0023A. We have evaluated bothmethods. Use of the improved Method0023A will not affect the achievabilityof the dioxin and furan standard.

In the proposal, we sought commenton the handling of nondetect values forcongeners analyzed using the dioxinand furan method. We also soughtcomment on whether the final ruleshould specify minimum samplingtimes. We proposed allowing facilitiesto assume that emissions of dioxins andfurans congeners are zero if the analysisshowed a nondetect for that congenerand the sample time for the test methodrun was at least 3 hours. See 61 FR17378. Dioxin/furan results may not beblank corrected. We received severalcomments this proposed approach,which are summarized below.

One commenter believes that aminimum dioxin/furan sampling time oftwo hours is sufficient. Anothercommenter believes that a minimumsample time as well as a minimumsample volume should be specified.Several commenters agree thatnondetects should be treated as zero(which is consistent with the Germanstandard) and prefer the three hourminimum sample period because thiswould help eliminate intra-laboratorydifferences and difficulties with matrixeffects in attaining low detection limits.One commenter believes that EPAshould specify the required detectionlimit for each congener analysis,otherwise the provision to assign zeroesto nondetected congeners in the TEQcalculation is open to abuse and couldresult in an understatement of the truedioxin/furan emissions. Thiscommenter also believes that a sourceshould not be allowed to sample dioxin/furans for time periods less than threehours, even if they assume nondetectsare present at the detection limit.

Upon carefully considering all theabove comments, we conclude that thefollowing approach best addresses thenondetect issue. The final rule requiresall sources to sample dioxin/furans fora minimum of three hours for each run,



250 See Final Technical Support Document,Volume IV, Chapter 3, for further discussion.

251 After further review and consideration of theGFCIR Method (322), we will not be promulgatingits use in the Portland Cement Kiln NESHAPrulemaking due to problems encountered with themethod during emission testing at limemanufacturing plants.

252 We note that this total train catch is notintended to be a data acceptance criteria. Thus, totaltrain catches exceeding 50 mg do not invalidate themethod.

and requires all sources to collect a fluegas sample of at least 2.5 dscm. Weconclude both these requirements arenecessary to maintain consistency fromsource to source, and to better assurethat the dioxin/furan emission resultsare accurate and representative. Weconclude that these two requirementsare achievable and appropriate 250.These requirements are consistent withthe requirements included in theproposed Portland Cement Kiln MACTrule (see 64 FR at 31898). The final rulealso allows a source to assume allnondetected congeners are not presentin the emissions when calculating TEQvalues for compliance purposes.

We considered whether it would beappropriate to specify requiredminimum detection limits for eachcongener analysis in order to betterassure that sources achieved reasonabledetection limits, as one commenterrecommended. Such a requirementwould prevent abuse andunderstatements of the true dioxin/furan emissions. We conclude, however,that it is not appropriate to finalizeminimum detection limits in thisrulemaking without giving theopportunity to all interested parties toreview and comment on such anapproach.

However, we are concerned that (1)sources have no incentive to achievelow detection limits; and (2) sourcesmay abuse the provision that allowsnondetected congener results to betreated as if they were not present. Asexplained in the Final TechnicalSupport Document referenced in thepreceding paragraph, if one assumesthat all dioxin/furan congeners arepresent at what we consider to be poordetection limits using Method 23A, theresultant TEQ can approach theemission standard. This outcome isclearly inappropriate from a complianceperspective.

As a result, we highly recommendthat this issue be addressed in thereview process of the performance testworkplan. Facilities should submitinformation that describes the targetdetection limits for all congeners, andcalculate a dioxin/furan TEQconcentration assuming all congenersare present at the detection limit(similar to what is done for riskassessments). If this value is close to theemission standard, both the source andthe regulatory official should determineif it is appropriate to either sample forlonger time periods or investigatewhether it is possible to achieve lowerdetection limits by using different

analytical procedures that are approvedby the Agency.

Also, EPA has developed analyticalstandards for certain mono-through tri-chloro dioxin and furan congeners. Weencourage you to test for thesecongeners in addition to the congenersthat comprise today’s standards. Thiscan be done at very little increased cost.If you test for these additionalcongeners, please include the results inyour Notification of Compliance. Wewould like this data so we can developa database from which to determinewhich (if any) of these compounds canact as surrogate(s) for the dioxin andfuran congeners which comprise thetotal and TEQ. If easily measurablesurrogate(s) can be found, we can thenstart the development of a CEMS forthese surrogates. A complete list ofthese congeners will be included in theimplementation document for this ruleand updated periodically throughguidance.

One commenter suggests that a sourcebe allowed to conduct one extendeddioxin/furan sampling event as opposedto three separate runs with threeseparate sampling trains because thiswould minimize the radioactive wastegenerated for sources that combustmixed waste. We conclude this issueshould be handled on a site-specificbasis, although an allowance of such anapproach seems reasonable. A sourcecan petition the Agency under theprovisions of § 63.7(f) for an alternativetest method for such a site-specificdetermination.

The final rule also adopts theapproach discussed in the December1997 NODA for sampling of mercury,semi-volatile metals, and low-volatilemetals. Therefore, for stack sampling ofmercury, semi-volatile metals, and low-volatile metals, you are required to useMethod 29 in 40 CFR part 60, appendixA. No adverse comments were receivedconcerning this approach in theDecember 1997 NODA.

For compliance with the hydrochloricacid and chlorine standards, today’srule requires that you use Method 26Ain 40 CFR part 60, appendix A.Commenters state that we shouldinstead require a method involving theFourier Transform Infrared and GasFilter Correlation Infrared instrumentaltechniques. Commenters contend thatMethod 26A is biased high at cementkilns because it collects ammoniumchloride in addition to the hydrochloricacid and chlorine gas emissions it wasdesigned to report. Commenters alsoindicate that the Fourier TransformInfrared and Gas Filter CorrelationInfrared were validated against Method26A and that these alternative methods

do not bias the results high due toammonium chloride 251. The data fortoday’s hydrochloric acid standard wasderived using the SW–846 equivalent toMethod 26A (Method 0050) as thereference method. Therefore, today’sstandard accounts for the ammoniumchloride collection bias. We reject theidea that we should require othermethods. If the commenters are correct,other methods would not sample theammonium chloride portion, thusmaking the standard less stringent. Youcan obtain Administrator approval forusing Fourier Transform Infrared or GasFilter Correlation Infrared techniquesfollowing the provisions found in 40CFR 63.7 if those methods are found topass a part 63, appendix A, Method 301validation at the source.

Compliance with the particulatematter standards requires the use ofeither Method 5 or Method 5i in 40 CFRpart 60, appendix A. See a relateddiscussion of Method 5i in Part 5,section VII.C.2.a of the preamble totoday’s rule. Although Method 5i hasbetter precision than Method 5, yourchoice of methods depends on theemissions during the performance test.In cases of low levels of particulatematter (i.e., for total train catches of lessthan 50 mg), we prefer that Method 5ibe used. For higher emissions, Method5 may be used 252. In practice this willlikely mean that all incinerators andmost lightweight aggregate kilns willuse Method 5i for compliance, whilesome lightweight aggregate kilns andmost cement kilns will use Method 5.

Today’s rule also allows the use ofany applicable SW–846 test methods todemonstrate compliance withrequirements of this subpart. As anexample, some commenters noted apreference to perform particulate matterand hydrochloric acid tests togetherusing Method 0050. Today’s rule wouldallow that practice. Applicable SW–846test methods are incorporated for useinto today’s rule via reference. Seesection 1208(a).

B. Sampling and Analysis ofFeedstreams

Today’s rule does not require the useof SW–846 methods for the samplingand analysis of feedstreams. Consistentwith our approach to move towardperformance based measurement



253 Feedstream sampling and analysis are notmethod defined parameters.

systems for other than method-definedparameters,253 today’s rule allows theuse of any reliable analytical method todetermine feedstream concentrations ofmetals, halogens, and otherconstituents. It is your responsibility toensure that the sampling and analysisare unbiased, precise, andrepresentative of the waste. For thewaste, you must demonstrate that: (1)Each constituent of concern is notpresent above the specification level atthe 80% upper confidence limit aroundthe mean; and (2) the analysis couldhave detected the presence of theconstituent at or below the specificationlevel at the 80% upper confidence limitaround the mean. You can refer to theGuidance for Data Quality Assessment—Practical Methods for Data Analysis,EPA QA/G–9, January 1998, EPA/600/R–96/084 for more information. Properselection of an appropriate analyticalmethod and analytical conditions (asallowed by the scope of that method) aredemonstrated by adequate recovery ofspiked analytes (or surrogate analytes)and reproducible results. Qualitycontrol data obtained must also reflectconsistency with the data qualityobjectives and intent of the analysis.You can read the January 31, 1996,memorandum from Barnes Johnson,Director of the Economics, Methods,and Risk Assessment Division, to James

Berlow, Director of the Hazardous WasteMinimization and Management Divisionfor more information on this topic.

IX. What Are the Reporting andRecordkeeping Requirements?

We discuss in this section reportingand recordkeeping requirements and aprovision in the rule for allowing datacompression to reduce therecordkeeping burden.

A. What Are the ReportingRequirements?

The reporting requirements of the ruleinclude notifications and reports thatmust be submitted to the Administratoras well as notifications, requests,petitions, and applications that youmust submit to the Administrator onlyif you elect to request approval tocomply with certain reduced oralternative requirements. Thesereporting requirements are summarizedin the following tables. We discusspreviously in various sections of today’spreamble the rationale for additional orrevised reporting requirements to thosecurrently required under subpart A ofpart 63 for all MACT sources. In othercases, the reporting requirements forhazardous waste combustors are thesame as for other MACT sources (e.g.,initial notification under existing§ 63.9(b). We also show in the tables the

reference(s) in the regulations for thereporting requirement.

SUMMARY OF NOTIFICATIONS THATYOU MUST SUBMIT TO THE ADMINIS-TRATOR

Reference Notification

63.9(b) ............ Initial notifications that youare subject to SubpartEEE.

63.1210(b) and(c).

Notification of intent to com-ply.

63.9(d) ............ Notification that you are sub-ject to special compliancerequirements.

63.1207(e),63.9(e)63.9(g) (1)and (3).

Notification of performancetest and continuous moni-toring system evaluation,including the performancetest plan and CMS per-formance evaluation plan.

163.1210(d),63.1207(j),63.9(h),63.10(d)(2),63.10(e)(2).

Notification of compliance,including results of per-formance tests and contin-uous monitoring systemperformance evaluations.

63.1206(b)(6) Notification of changes indesign, operation, or main-tenance.

63.9(j) ............. Notification and documenta-tion of any change in infor-mation already providedunder § 63.9.

1 You may also be required on a case-by-case basis to submit a feedstream analysisplan under § 63.1209(c)(3).

SUMMARY OF REPORTS THAT YOU MUST SUBMIT TO THE ADMINISTRATOR

Reference Report

63.1211(b) .................................................................... Compliance progress report associated and submitted with the notification of intent tocomply.

63.10(d)(4) ................................................................... Compliance progress reports, if required as a condition of an extension of the compli-ance date granted under § 63.6(i).

63.1206(c)(3)(vi) .......................................................... Excessive exceedances reports.63.1206(c)(4)(iv) .......................................................... Emergency safety vent opening reports.63.10(d)(5)(i) ................................................................ Periodic startup, shutdown, and malfunction reports.63.10(d)(5)(ii) ............................................................... Immediate startup, shutdown, and malfunction reports.63.10(e)(3) ................................................................... Excessive emissions and continuous monitoring system performance report and sum-

mary report.

SUMMARY OF NOTIFICATIONS, REQUESTS, PETITIONS, AND APPLICATIONS THAT YOU MUST SUBMIT TO THEADMINISTRATOR ONLY IF YOU ELECT TO COMPLY WITH REDUCED OR ALTERNATIVE REQUIREMENTS

Reference Notification, request, petition, or application

63.1206(b)(5), 63.1213, 63.6(i), 63.9(c) ...................... You may request an extension of the compliance date for up to one year.63.9(i) ........................................................................... You may request an adjustment to time periods or postmark deadlines for submittal and

review of required information.63.1209(g)(1) ............................................................... You may request approval of: (1) alternative monitoring methods, except for standards

that you must monitor with a continuous emission monitoring system (CEMS) and ex-cept for requests to use a CEMS in lieu of operating parameter limits; or (2) a waiverof an operating parameter limit.

63.1209(a)(5), 63.8(f) ................................................... You may request: (1) approval of alternative monitoring methods for compliance withstandards that are monitored with a CEMS; and (2) approval to use a CEMS in lieu ofoperating parameter limits.



SUMMARY OF NOTIFICATIONS, REQUESTS, PETITIONS, AND APPLICATIONS THAT YOU MUST SUBMIT TO THEADMINISTRATOR ONLY IF YOU ELECT TO COMPLY WITH REDUCED OR ALTERNATIVE REQUIREMENTS—Continued

Reference Notification, request, petition, or application

63.1204(d)(4) ............................................................... Notification that you elect to comply with the emission averaging requirements for ce-ment kilns with in-line raw mills.

63.1204(e)(4) ............................................................... Notification that you elect to comply with the emission averaging requirements for pre-heater or preheater/precalciner kilns with dual stacks.

63.1206(b)(1)(ii)(A) ...................................................... Notification that you elect to document compliance with all applicable requirements andstandards promulgated under authority of the Clean Air Act, including Sections 112and 129, in lieu of the requirements of Subpart EEE when not burning hazardouswaste.

63.1206(b)(9)(iii)(B) ...................................................... If you elect to conduct particulate matter CEMS correlation testing and wish to have fed-eral particulate matter and opacity standards and associated operating limits waivedduring the testing, you must notify the Administrator by submitting the correlation testplan for review and approval.

63.1206(b)(10) ............................................................. Owners and operators of lightweight aggregate kilns may request approval of alternativeemission standards for mercury, semivolatile metal, low volatile metal, and hydrochloricacid/chlorine gas under certain conditions.

63.1206(b)(11) ............................................................. Owners and operators of cement kilns may request approval of alternative emissionstandards for mercury, semivolatile metal, low volatile metal, and hydrochloric acid/chlorine gas under certain conditions.

63.1207(c)(2) ............................................................... You may request to base initial compliance on data in lieu of a comprehensive perform-ance test.

63.1207(i) ..................................................................... You may request up to a one-year time extension for conducting a performance test(other than the initial comprehensive performance test) to consolidate testing withother state or federally-required testing.

63.1209(l)(1) ................................................................ You may request to extrapolate mercury feedrate limits.63.1209(n)(2)(ii) ........................................................... You may request to extrapolate semivolatile and low volatile metal feedrate limits.63.10(e)(3)(ii) ............................................................... You may request to reduce the frequency of excess emissions and CMS performance

reports.63.10(f) ......................................................................... You may request to waive recordkeeping or reporting requirements.63.1211(e) .................................................................... You may request to use data compression techniques to record data on a less frequent

basis than required by § 63.1209.

Some commenters suggest that therule needs to provide additionalreporting of information regardingmetals fed to cement kilns, includingquarterly reporting of daily averagemetal feedrates, maximum hourlyfeedrates, and all testing and analyticalinformation on the toxic metal contentof cement kiln dust and clinker product.Also, they suggest that toxic metals thatare Toxics Release Inventory pollutantsand that are released to the land fromcement kiln dust disposal should bereported. While these reports mighthave some value for other purposes, wemust carefully scrutinize all reportingand recordkeeping burdens for arulemaking and determine whether thereporting and recordkeepingrequirements are necessary to ensurecompliance with the standards. (We, asan agency, cannot increase overall ourreporting and recordkeeping burden.)

We do not believe that these reportsare needed to ensure compliance withthe standards and therefore are notrequiring them. On balance, quarterlyfiling requirements would be too

burdensome. A source must documentcompliance with all operating parameterlimits and emission standards at alltimes, and its records are subject toinspection at any time. There is noadditional need to provide quarterlyreports.

One commenter suggests that theproposed rule incorrectly focuses onmaximizing data collection as opposedto ensuring performance, thusfrustrating the use of better technologyand methods. We, of course, are alsointerested in ensuring performance byall reasonable means, which forexample accounts for our continuedfocus on continuous emission monitors.However, we are not able to sacrificedata collection as a means for ensuringcompliance as well as a means toundergird future rulemakings, assessachievability, and determine site-specific compliance limits, wherenecessary.

B. What Are the RecordkeepingRequirements?

You must keep the recordssummarized in the table below for at

least five years from the date of eachoccurrence, measurement, maintenance,corrective action, report, or record. Seeexisting § 63.10(b)(1). At a minimum,you must retain the most recent twoyears of data on site. You may retain theremaining three years of data off site.You may maintain such files on:microfilm, a computer, computer floppydisks, optical disk, magnetic tape, ormicrofiche.

We discuss previously in varioussections of today’s preamble therationale for additional or revisedrecordkeeping requirements to thosecurrently required under subpart A ofpart 63 for all MACT sources. In othercases, the recordkeeping requirementsfor hazardous waste combustors are thesame as for other MACT sources (e.g.,record of the occurrence and duration ofeach malfunction of the air pollutioncontrol equipment; see existing§ 63.10(b)(2)(ii)). We also show in thetable the reference(s) in the regulationsfor the recordkeeping requirement.



SUMMARY OF DOCUMENTS, DATA, ANDINFORMATION THAT YOU MUST IN-CLUDE IN THE OPERATING RECORD

Reference Document, data, or informa-tion

63.1201(a),63.10 (b)and (c).

General. Information re-quired to document andmaintain compliance withthe regulations of SubpartEEE, including data re-corded by continuousmonitoring systems(CMS), and copies of allnotifications, reports,plans, and other docu-ments submitted to theAdministrator.

63.1211(d) ...... Documentation of compli-ance.

63.1206(c)(3)(vii).

Documentation and resultsof the automatic wastefeed cutoff operability test-ing.

63.1209 (c)(2) Feedstream analysis plan.63.1204 (d)(3) Documentation of compli-

ance with the emissionaveraging requirements forcement kilns with in-lineraw mills.

63.1204 (e)(3) Documentation of compli-ance with the emissionaveraging requirements forpreheater or preheater/precalciner kilns with dualstacks.

63.1206(b)(1)(ii)(B).

If you elect to comply with allapplicable requirementsand standards promul-gated under authority ofthe Clean Air Act, includ-ing Sections 112 and 129,in lieu of the requirementsof Subpart EEE when notburning hazardous waste,you must document in theoperating record that youare in compliance withthose requirements.

63.1206 (c)(2) Startup, shutdown, and mal-function plan.

SUMMARY OF DOCUMENTS, DATA, ANDINFORMATION THAT YOU MUST IN-CLUDE IN THE OPERATINGRECORD—Continued

Reference Document, data, or informa-tion

63.1206(c)(3)(v).

Corrective measures for anyautomatic waste feed cut-off that results in an ex-ceedance of an emissionstandard or operating pa-rameter limit.

63.1206(c)(4)(ii).

Emergency safety vent oper-ating plan.

63.1206(c)(4)(iii).

Corrective measures for anyemergency safety ventopening.

63.1206 (c)(6) Operator training and certifi-cation program.

63.1209(k)(6)(iii),63.1209(k)(7)(ii),63.1209(k)(9)(ii),63.1209(o)(4)(iii).

Documentation that a sub-stitute activated carbon,dioxin/furan formation re-action inhibitor, or dryscrubber sorbent will pro-vide the same level ofcontrol as the original ma-terial.

Some commenters are concerned thatthe specification of media on whichthese files may be maintainedunnecessarily limits the options tofacilities, especially those not equippedwith computer or other electronic datagathering equipment. We conclude,however, that the options listed under§ 63.10(b)(1) seem to provide thegreatest flexibility possible, includingthe reasonable management of paperrecords through the use of microfilm ormicrofiche. We encourage the use ofcomputer and electronic equipment,however, for logistical reasons (retrievaland inspection can be easier) and as ameans to enhance dissemination to thelocal community to foster anatmosphere of full and open disclosureabout facility operations.

C. How Can You Receive Approval toUse Data Compression Techniques?

You may submit a written request tothe Administrator under § 63.1211(f) forapproval to use data compressiontechniques to record data from CMS,including CEMS, on a frequency lessthan that required by § 63.1209. Youmust submit the request for review andapproval as part of the comprehensiveperformance test plan. For each CEMSor operating parameter for which yourequest to use data compressiontechniques, you must provide: (1) Afluctuation limit that defines themaximum permissible deviation of anew data value from a previouslygenerated value without requiring youto revert to recording each one-minuteaverage; and (2) a data compressionlimit defined as the closest level to anoperating parameter limit or emissionstandard at which reduced recording isallowed.

You must record one-minute averagevalues at least every ten minutes. If afterexceeding a fluctuation limit youremain below the limit for a ten-minuteperiod, you may reinitiate your datacompression technique provided thatyou are not exceeding the datacompression limit.

The fluctuation limit should representa significant change in the parametermeasured, considering the range ofnormal values. The data compressionlimit should reflect a level at which youare unlikely to exceed the specificoperating parameter limit or emissionstandard, considering its averagingperiod, with the addition of a new one-minute average.

We provide the following table ofrecommended fluctuation and datacompression limits as guidance. Theseare the same limits that we discussed inthe May 1997 NODA.

RECOMMENDED FLUCTUATION AND DATA COMPRESSION LIMITS

CEMS or control technique and parameter Fluctuation limit (±) Data compression limit

Continuous Emission Monitoring System:Carbon monoxide .......................................................................................................... 10 ppm ...................... 50 ppm.Hydrocarbon .................................................................................................................. 2 ppm ........................ 60% of standard.

Combustion Gas Temperature Quench: Maximum inlet temperature for dry particulatematter control device or, for lightweight aggregate kilns, temperature at kiln exit.

10°F ........................... Operating parameter limit(OPL) minus 30°F.

Good Combustion Practices:Maximum gas flowrate or kiln production rate .............................................................. 10% of OPL ............... 60% of OPL.Maximum hazardous waste feedrate ............................................................................ 10% of OPL ............... 60% of OPL.Maximum gas temperature for each combustion chamber ........................................... 20°F ........................... OPL plus 50°F.

Activated Carbon Injection:Minimum carbon injection feedrate ............................................................................... 5% of OPL ................. OPL plus 20%.Minimum carrier fluid flowrate or nozzle pressure drop ................................................ 20% of OPL ............... OPL plus 25%.

Activated Carbon Bed: Maximum gas temperature at inlet or exit of the bed ..................... 10°F ........................... OPL minus 30°F.Catalytic Oxidizer:

Minimum flue gas temperature at entrance .................................................................. 20°F ........................... OPL plus 40°F.Maximum flue gas temperature at entrance ................................................................. 20°F ........................... OPL minus 40°F.

Dioxin Inhibitor: Minimum inhibitor feedrate ......................................................................... 10% of OPL ............... 60% of OPL.Feedrate Control:



RECOMMENDED FLUCTUATION AND DATA COMPRESSION LIMITS—Continued

CEMS or control technique and parameter Fluctuation limit (±) Data compression limit

Maximum total metals feedrate (all feedstreams) ......................................................... 10% of OPL ............... 60% of OPL.Maximum low volatile metals feedrate, pumpable feedstreams ................................... 10% of OPL ............... 60% of OPL.Maximum total ash feedrate (all feedstreams) .............................................................. 10% of OPL ............... 60% of OPL.Maximum total chlorine feedrate (all feedstreams) ....................................................... 10% of OPL ............... 60% of OPL.

Wet scrubber:Minimum pressure drop across scrubber ...................................................................... 0.5 inches water ........ OPL plus 2 inches water.Minimum liquid feed pressure ....................................................................................... 20% of OPL ............... OPL plus 25%.Minimum liquid pH ......................................................................................................... 0.5 pH unit ................. OPL plus 1 pH unit.Maximum solids content in liquid .................................................................................. 5% of OPL ................. OPL minus 20%.Minimum blowdown (liquid flowrate) ............................................................................. 5% of OPL ................. OPL plus 20%.Minimum liquid flowrate or liquid flowrate/gas flowrate ratio ........................................ 10% of OPL ............... OPL plus 30%.

Dry scrubber:Minimum sorbent feedrate ............................................................................................. 10% of OPL ............... OPL plus 30%.Minimum carrier fluid flowrate or nozzle pressure drop ................................................ 10% of OPL ............... OPL plus 30%.

Fabric filter: Minimum pressure drop across device ............................................................ 1 inch water ............... OPL plus 2 inches water.Electrostatic precipitator and ionizing wet scrubber: Minimum power input (kVA: current

and voltage).5% of OPL ................. OPL plus 20%.

Data compression is the process bywhich a facility automatically evaluateswhether a specific data point needs tobe recorded. Data compression does notrepresent a change in the continuousmonitoring requirement in the rule.One-minute averages will continue to begenerated. With data compression,however, each one-minute average isautomatically compared with a set ofspecifications (i.e., fluctuation limit anddata compression limit) to determinewhether it must be recorded. New dataare recorded when the one-minuteaverage value falls outside thesespecifications.

We did not propose data compressiontechniques in the April 1996 NPRM. Inresponse to the proposed monitoringand recording requirements, however,commenters raise concerns about theburden of recording one-minute averagevalues for the array of operatingparameter limits that we proposed.Commenters suggest that allowing datacompression would significantly reducethe recordkeeping burden whilemaintaining the integrity of the data forcompliance monitoring. We note thatdata compression should also benefitregulatory officials by allowing them tofocus their review on those data that areindicative of nonsteady-state operationsand that are close to the operatingparameter limit or, for CEMS, theemission standard.

In response to these concerns, wepresented data compressionspecifications in the May 1997 NODA.Public comments on the NODA areuniformly favorable. Therefore, we areincluding a provision in the final rulethat allows you to request approval touse data compression techniques. Thefluctuation and data compression limitspresented above are offered as guidanceto assist you in developing your

recommended data compressionmethodology.

We are not promulgating datacompression specifications because thedynamics of monitored parameters arenot uniform across the regulateduniverse. Thus, establishing nationalspecifications would be problematic.Various data compression techniquescan be successfully implemented for amonitored parameter to obtaincompressed data that reflect theperformance on a site-specific basis.Thus, the rule requires you torecommend a data compressionapproach that addresses the specifics ofyour operations. The fluctuation anddata compression limits presentedabove are offered solely as guidance andare not required.

The rule requires that you record avalue at least once every ten minutes toensure that a minimum, credible database is available for compliancemonitoring. If you operate under steady-state conditions at levels well belowoperating parameter limits and CEMS-monitored emission standards, datacompression techniques may enable youto achieve a potential reduction in datarecording up to 90 percent.

X. What Special Provisions AreIncluded in Today’s Rule?

A. What Are the Alternative Standardsfor Cement Kilns and LightweightAggregate Kilns?

In the May 1997 NODA, we discussedalternative standards for cement kilnsand lightweight aggregate kilns thathave metal or chlorine concentrations intheir mineral and related process rawmaterials that might cause anexceedance of today’s standard(s), eventhough the source uses MACT control.(See 62 FR 24238.) After carefullyconsidering commenters input, we

adopt a process that allows sources topetition the Administrator foralternative mercury, semivolatile metal,low volatile metal, or hydrochloric acid/chlorine gas standards under twodifferent sets of circumstances. Onereason for a source to consider a petitionis when a kiln cannot achieve thestandard, while using MACT control,because of raw material contributions totheir hazardous air pollutant emissions.The second reason is limited tomercury, and applies when mercury isnot present at detectable levels in thesource’s raw material. These alternativestandards are discussed separatelybelow.

1. What Are the Alternative StandardsWhen Raw Materials Cause anExceedance of an Emission Standard?See sections 1206(b) (10) and (11)

a. What Approaches Have WePublicly Discussed? We acknowledgethat a kiln using properly designed andoperated MACT control technologies,including control of metals levels inhazardous waste feedstocks, may not becapable of achieving the emissionstandards (i.e., the mercury,semivolatile metal, low volatile metal,and/or hydrochloric acid/chlorine gasstandards). This can occur whenhazardous air pollutants (i.e., metalsand chlorine) contained in the rawmaterial volatilize or are entrained inthe flue gas such that their contributionto total metal and chlorine emissionscause an exceedance of the emissionstandard.

Our proposal first acknowledged thispossible situation. In the April 1996NPRM, we proposed metal and chlorinestandards that were based, in part, onspecified levels of hazardous wastefeedrate control as MACT control. Toaddress our concern that kilns may not



254 We could not estimate a cement kiln’s totalemissions (i.e., to determine emission standardachievability) based on the assumption that the kilnis feeding metals in the hazardous waste at theMACT control feedrate levels.

255 As explained earlier, the emission standardsfor metals and chlorine reflect the performance ofMACT control, which includes control of metalsand chlorine in the hazardous waste feed materials.As further explained, sources are not required toadopt MACT control. Sources must, however,achieve the level of performance which MACTcontrol achieves. Therefore, sources are notrequired to control metals and chlorine hazardouswaste feedrates to the same levels as MACT controlin order to comply with the standards for metalsand chlorine. Rather, the source can elect to achievethe emission standard by any means, which may ormay not involve hazardous waste feedrate control

256 H.R. Rep. No. 101–952, at p. 339, 101st Cong.,2d Sess. (Oct. 26, 1990).

257 See 62 FR 24239, May 2, 1997.258 The nonhazardous waste Portland Cement

Kiln MACT rulemaking likewise controls

semivolatile metal and low volatile metal emissionsby limiting particulate matter emissions, and didnot adopt beyond-the-floor standards based on rawmaterial metal and chlorine feedrate control—see64 FR 31898.

259 When estimating emissions, the Agencyassumed the kiln was feeding metals and chlorinein its hazardous waste at the lower of the MACTdefining maximum theoretical emissionconcentration levels or the level actuallydemonstrated during its performance test. See FinalTechnical Support Document for Hazardous WasteCombustor MACT Standards, Volume II: Selectionof MACT Standards and Technologies, July 1999,for further discussion.

be able to achieve the standards whenusing MACT control technologies, givenraw material contributions to emissions,we performed an analysis. Our analysisestimated the total emissions of eachkiln including emissions from rawmaterials, while also assuming thesource was using MACT hazardouswaste feedrate and particulate mattercontrol. Results of this analysis, whichwere discussed in the proposal,indicated that there may be several kilnsthat would not be able to achieve theproposed emission standards whileusing MACT control, due to levels ofmetals and chlorine in raw materialand/or conventional fuel. (See 61 FR at17393–17406.) Commenters requestedthat we provide an equivalencydetermination to allow sources tocomply with a control efficiencyrequirement (e.g., a minimum metalsystem removal efficiency) in lieu of theemission standard. (See responsebelow.)

In the May 1997 NODA, we discussedrevised standards that defined MACTcontrol, in part, based on hazardouswaste metal and chlorine feedratecontrol—as did the NPRM. (See 62 FR24225–24235.) However, our revisedapproach did not define specific levelsof hazardous waste metal and chlorinefeedrate control, therefore, making itdifficult to attribute a kiln’s failure tomeet emission standards to metalslevels in raw materials.254 In response toa commenter’s request, we discussed, inthe May 1997 NODA, an alternativeapproach to address raw materialcontributions. Our approach did notsubject a source to the MACT standardsif the source could document that metalor chlorine concentrations in theirhazardous waste, and any nonmineralfeedstock, is within the range of normalindustry levels. The purpose of thisrequirement was to ensure that metaland chlorine emissions attributable tononmineral feedstreams were roughlyequivalent to those from sourcesachieving the MACT emissionstandards. The use of an industryaverage, or normal metal and chlorinelevel, was to serve as a surrogate MACTfeedrate control level for the alternativestandard because we did not define aspecific level of control as MACT. Wealso requested comment on how best todetermine normal hazardous wastemetal and chlorine levels.

Today’s final rule uses a revisedstandard setting methodology thatdefines specific levels of hazardous

waste metal and chlorine feedrates asMACT control.255 As a result, we do notneed to define normal, or average, metaland chlorine levels for the purposes ofthis alternative standard provision.

b. What Comments Did We Receiveon Our Approaches? There were manycomments supporting and manyopposing the concept of allowingalternative standards. Severalcommenters focus on the Agency’s legalbasis for this type of alternativestandard. Some, supporting analternative standard, wrote that feedratecontrol of raw materials at mineralprocessing plants is not a permissiblebasis for MACT control. In support oftheir position, some directed ourattention to the language found in theConference Report to the 1990 CAAamendments.256 However, as we notedin the April 1996 NPRM and as wasmentioned by many commenters 257, theConference Report language is notreflected in the statute. Section112(d)(2)(A) of the statute states,without caveat, that MACT standardsmay be based on ‘‘process changes,substitution of materials or othermodifications.’’

As noted above, our MACT approachin today’s rule relies on metal andchlorine hazardous waste feedratecontrol as part of developing MACTemission standards. It should be noted,that we do not directly regulate rawmaterial metal and chlorine input underthis approach, although there is no legalbar for us to do so. Since raw materialfeedrate control is not an industrypractice, raw material feedrate control isnot part of the MACT floor. In addition,we do not adopt such control as abeyond-the-floor standard. We concludeit is not cost-effective to require kilns tocontrol metal and chlorine emissions bysubstituting their current raw materialswith off-site raw materials. (See metaland chlorine emission standarddiscussions for cement kilns andlightweight aggregate kilns in Part Four,Sections VII and VIII.) 258

Although today’s rule offers a petitionprocess, we considered varying levels ofmetal and chlorine emissionsattributable to raw material inidentifying the metal and chlorineemission standards through our MACTfloor methodology. This considerationhelps to ensure that the emissionstandards are achievable for sourcesusing MACT control. Therefore, weanticipate very few sources, if any, willneed to petition the Administrator foralternative standards. However, it ispossible that raw material hazardous airpollutant levels, at a given kiln location,could vary over time and preclude kilnsfrom achieving the emission standards.We believe, therefore, that it isappropriate to adopt a provision toallow kilns to petition for alternativestandards so that future changes in rawmaterial feedstock will not preventcompliance with today’s emissionstandards.

Other commenters believe thatalternative standards are not necessarybecause there are kilns with relativelyhigh raw material metal concentrationsalready achieving the proposedstandards. To address this point, and toreevaluate the ability of kilns to achievethe emission standards without newcontrol of metals and chlorine in rawmaterial and conventional fuel, weagain estimated the total metal andchlorine emissions, assuming each kilnfed metal and chlorine at the definedMACT feedrate control levels.259

The following table summarizes theestimated achievability of the emissionstandards assuming kilns used MACTcontrol. Our analysis determinedachievability both at the emissionstandard and at the design level—70percent of the standard. (To ensurecompliance most kilns will ‘‘design’’their system to operate, at a minimum,30 percent below the standard.) Thetable describes the number of testconditions in our data base that wouldnot meet the emission standard or meetthe design level by estimating totalemissions. For example, all cement kilntest conditions achieve the mercuryemission standard, assuming all cement



260 The potential for increased metal emissions isstronger for semivolatile metals (lead, in particular),but low volatile metal emissions still have potentialto increase with increased flue gas chlorineconcentrations. See Final Technical SupportDocument for Hazardous Waste Combustor MACT

Standards, Volume II: Selection of MACT Standardsand Technologies, July 1999, for further discussion.

261 RCRA permits for hazardous waste combustorsaddress total emissions, regardless of the source ofthe pollutant due to the nexus with the hazardouswaste treatment activities. See Horsehead vBrowner, 16 F. 3d 1246, 1261–63 (D.C. Cir.1994)(Hazardous waste combustion standards mayaddress hazardous constituents attributable to rawmaterial inputs so long as thee is a reasonable nexuswith the hazardous waste combustion activites).

kilns used MACT control. On the otherhand, the table also indicates that fourcement kiln test conditions out of 27 donot achieve the design level for

mercury. In our analysis, if all testconditions achieved both the standardand the design level, we concluded thatthere is no reason to believe raw

material contributions to metal andchlorine emissions might cause acompliance problem.

CEMENT KILN AND LIGHTWEIGHT AGGREGATE KILN EMISSION STANDARD ACHIEVABILITY RESULTS

Source category Mer-cury

Semivolatilemetal

LowVolatilemetal

Totalchlo-rine

No. of cement kiln test conditions in MACT data base not achieving standard ...................................... 10/27 11/38 11/39 12/42No of cement kiln test conditions in MACT data base not achieving 70 % design level ........................ 4/27 6/38 3/39 3/42No of lightweight aggregate kiln test conditions in MACT data base not achieving standard ................ 0/17 5/22 2/22 3/18No of lightweight aggregate kiln test conditions in MACT data base not achieving 70% design level .. 0/17 5/22 4/22 10/18

*Number after slash denotes total number of test conditions.

Our analysis illustrates that, subject tothe assumptions made, somelightweight aggregate kilns and cementkilns have raw material hazardous airpollutant levels that could affect theirability to achieve the emission standardif no additional emission controls wereimplemented (e.g., additional hazardouswaste feedrate control, or better airpollution control device efficiency).Nevertheless, we conclude that it isdifficult to determine whether rawmaterial hazardous air pollutantcontributions to the emissions result inunachievable emission standardsbecause of the difficulty associated withdifferentiating raw material hazardousair pollutant emissions from hazardouswaste pollutant emissions. Thisuncertainty has led us to furtherconclude that it is appropriate to allowkilns to petition for alternativestandards, provided that they submitsite-specific information that shows rawmaterial hazardous air pollutantcontributions to the emissions preventthe kiln from complying with theemission standard even though the kilnis using MACT control.

Many commenters dislike the idea ofan alternative standard. They wrote thatregulation of raw material metal contentmay be necessary to control semivolatilemetal and low volatile metal emissionsat hazardous waste burning kilnsbecause: (1) These kilns have relativelyhigh chlorine levels in the flue gas(which predominately originate fromthe hazardous waste); and (2) chlorinetends to increase metal volatility. Weagree that increased flue gas chlorinecontent from hazardous waste burningoperations may result in increasedmetals volatility, which then couldresult in higher raw material metalemissions.260 The increased presence of

chlorine at hazardous waste burningkilns presents a concern. To address thisconcern, we require kilns to submit dataor information, as part of the alternativestandard petition, documenting thatincreased chlorine levels associatedwith the burning of hazardous waste, ascompared to nonhazardous wasteoperations, do not significantly increasemetal emissions attributable to rawmaterial. This requirement is explainedin greater detail later in this section.

Many commenters also point out thatthe alternative standard, at least asoriginally proposed, could result inmetal and chlorine emissions exceedingthe standard to possible levels of risk tohuman health and the environment. Weagree that this potential could exist;however, the RCRA omnibus processserves as a safeguard against levels ofemissions that present risk to humanhealth or the environment. Therefore,sources operating pursuant toalternative standards may likely berequired to perform a site-specific riskassessment to demonstrate that theiremissions do not pose an unacceptablerisk. The results of the risk assessmentwould then be used to develop facility-specific metal and chlorine emissionlimits (if necessary), which would beimplemented and enforced throughomnibus conditions in the RCRApermit.261

c. How Do I Demonstrate Eligibilityfor the Alternative Standard? Todemonstrate eligibility, you must submitdata or information which shows thatraw material hazardous air pollutantcontributions to the emissions preventyou from complying with the emission

standard, even though you use MACTcontrol for the standard from which youseek relief. To allow flexibility inimplementation, we do not mandatewhat this demonstration must entail.However, we believe that ademonstration should include aperformance test while using MACTcontrol or better (i.e., the hazardouswaste feedrate control and air pollutioncontrol device efficiencies that are thebasis of the emission standard fromwhich you seek an alternative). If youstill do not achieve the emissionstandards when operating under theseconditions, you may be eligible for thealternative standard (provided youfurther demonstrate that you meet theadditional eligibility requirementsdiscussed below). If you choose toconduct this performance test after yourcompliance date, you should first obtainapproval to temporarily exceed theemission standards (for testing purposesonly) to make this demonstration,otherwise you may be subject toenforcement action.

In addition, you must make a showingof adequate system removal efficiency tobe eligible for an alternative standard forsemivolatile metal, low volatile metal,or hydrochloric acid/chlorine gas. Thisrequirement provides a check to ensurethat you are exceeding the emissionstandard solely because of raw materialcontributions to the emissions, and notbecause of poor system removalefficiency for the hazardous airpollutants for which you are seekingrelief. (It is possible that poor systemremoval efficiencies for these hazardousair pollutants result in emissions thatare higher than the emission standards,even though the particulate matteremission standard is met.) This checkcould be done without the expense of asecond performance test. The systemremoval efficiency achieved in theperformance test described above couldbe calculated for the hazardous airpollutants at issue. You would then



You may choose to comply with a hazardouswaste feedrate limit that is lower than the MACTcontrol levels required by this alternative standard.

263 The requirement to achieve an 85.0% and99.6% chlorine system removal efficiency forexisting and new lightweight aggregate kilns,respectively, together with the requirement tocomply with a hazardous waste chlorine feedratelimitation, ensures that chlorine emissionsattributable to hazardous waste are below thestandards.

264 The MACT defining hazardous wastemaximum theoretical emission concentration formercury is less than mercury standard itself, thushazardous waste mercury contributions to theemissions will always be below the standard.

265 There is no corresponding chlorine airpollution control device efficiency requirement forcement kilns since air pollution control is not thebasis for MACT control of cement kiln chlorineemissions.

266 See also ‘‘Final Technical Support Documentfor Hazardous Waste Combustor MACT Standards,

Volume IV: Selection of MACT Standards andTechnologies’’, Chapter 11, July 1999, for furtherdiscussion on how the maximum achievable controltechnologies were chosen for the hazardous airpollutants.

multiply the MACT control hazardouswaste feedrate level (or the feedratelevel you choose to comply with) 262 forthe same hazardous air pollutant by afactor of one minus the system removalefficiency. This estimated emissionvalue would then be compared to theemission standard, and would have tobe below the standard for you to qualifyfor the alternative standard.

As discussed in the next section, thisalternative standard requires you to useMACT control as defined in thisrulemaking. For lightweight aggregatekilns, MACT control for chlorine isfeedrate control and use of an airpollution control system that achieves agiven system removal efficiency forchlorine. Thus, lightweight aggregatekilns that petition the Administrator foran alternative chlorine standard mustalso demonstrate, as part of aperformance test, that it achieves aspecified minimum system removalefficiency for chlorine. This eligibilityrequirement is identical to the above-mentioned eligibility demonstration thatrequires sources to make a showing ofadequate system removal efficiency,with the exception that here we specifythe system removal efficiency that mustbe achieved.263

For an alternative mercury standard,you do not have to perform aperformance test demonstration andevaluation. We do not require this testbecause the mandatory hazardous wastemercury feedrate specified in§ 63.1206(b)(10) and (11) ensures thatyour hazardous waste mercurycontribution to the emissions willalways be below the mercurystandard.264

Finally, if you apply for semivolatilemetal or low volatile metal alternativestandards, you also must demonstrate,by submitting data or information, thatincreased chlorine levels associatedwith the burning of hazardous waste, ascompared to nonhazardous wasteoperations, do not significantly increasemetal emissions attributable to rawmaterial. We expect that you will haveto conduct two different emission teststo make this demonstration (although

the number of tests should bedetermined on a site-specific basis). Thefirst test is to determine metal emissionconcentrations when the kiln is burningconventional fuel with typical chlorinelevels. The second test is to determinemetal emissions when chlorinefeedrates are equivalent to allowablechlorine feedrates when burninghazardous waste. You should structurethese tests so that metal feedrates forboth tests are equivalent. You wouldthen compare metal emission data todetermine if increased chlorine levelssignificantly affects raw material metalemissions.

d. What Is the Format of theAlternative Standard? The alternativestandard requires that you use MACTcontrol, or better, as applicable to thestandard for which you seek thealternative. MACT control, aspreviously discussed, consists ofhazardous waste feed control plus (forall relevant hazardous air pollutantsexcept mercury) further control via airpollution control devices. Cement kilnsand lightweight aggregate kilns will firsthave to comply with a specifiedhazardous waste metal and chlorinefeedrate limit, as defined by the MACTdefining maximum theoretical emissionconcentration level for the applicablehazardous air pollutant or hazardous airpollutant group. This work practice isnecessary because there is no otherreliable means of measuring thathazardous air pollutants in hazardouswaste are controlled to the MACTcontrol levels, i.e., that hazardous airpollutants in raw material are the solecause of not achieving the emissionstandard. (See CAA section 112(h).) Todemonstrate control of hazardous airpollutant metals emissions to levelsreflecting the air pollution controldevice component of MACT control,you must be in compliance with theparticulate matter standard. Finally, werequire lightweight aggregate kilns touse an air pollution control device thatachieves the specified MACT controltotal chlorine removal efficiency. Thiswork practice is necessary because thereis no other way to measure whether thefailure to achieve the chlorine emissionstandard is caused by chlorine levels inraw materials.265 See § 63.1206(b)(10)and (11) for a list of the maximumachievable control technologyrequirements for purposes of thisalternative standard.266

There may be site-specificcircumstances which require otherprovisions, imposed by theAdministrator, in addition to themandatory requirement to use MACTcontrol. These provisions could beoperating parameter requirements suchas a further hazardous waste feedratelimitation. For instance, a kiln thatpetitions the Administrator for analternative semivolatile emissionstandard may need to limit itshazardous waste chlorine feedrate tobetter assure that chlorine originatingfrom the hazardous waste does notsignificantly affect semivolatile metalemissions attributable to the rawmaterial. As discussed above, a kilnmust demonstrate that increasedchlorine levels from hazardous waste donot adversely affect raw material metalemissions to be eligible for thisalternative standard. For this scenario,the alternative standard would be in theform of a semivolatile metal hazardouswaste feedrate restriction which wouldrequire you to use MACT control, inaddition to a hazardous waste chlorinefeedrate limit.

Additional provisions also couldinclude emission limitations that differfrom those included in today’srulemaking. For example, theAdministrator may determine itappropriate to require you to complywith metal or chlorine emissionlimitations that are than the standardsin this final rulemaking. The emissionlimitation would likely consider theelevated levels of metal or chlorine inyour raw material. This type of emissionlimitation would be no different, exceptfor the numerical difference than theemission limitations in today’s rulebecause it would limit total metal andchlorine emissions while at the sametime ensuring MACT control is used. Ifthe Administrator determines that suchan emission limitation is appropriate,you must comply with both a hazardouswaste feedrate restriction, whichrequires you to use MACT control, andan emission limitation. A potentialmethod of determining an appropriateemission limitation would be to base thelimit on levels demonstrated in thecomprehensive performance test.

e. What Is the Process for anAlternative Standard Petition? If you areseeking alternative standards becauseraw materials cause you to exceed thestandards, you must submit a petitionrequest to the Administrator thatincludes your recommended alternative



267 The provisions in § 63.1207(m) waive therequirement for you to conduct a performance test,and the requirement to set operating limits based onperformance test data, provided you demonstratethat uncontrolled mercury emissions are below theemission standard (see Part 4, Section X.B). Theseprovisions allow you to assume mercury is presentat half the detection limit in the raw material, when

a feedstream analysis determines that mercury isnot present at detectable levels, when calculatingyour uncontrolled emissions.

268 Kilns that comply with alternative mercurystandards because of high mercury levels in theirraw material are not required to monitor themercury content of their raw material unless theAdministrator requires this as an additionalalternative standard requirement. Thus, absent thealternative mercury standard discussed in thissection, a source that does not have mercurypresent in their mercury at detectable levels wouldbe subject to more burdensome raw materialfeedstream analysis requirements.

269 Also see Final Technical Support Documentfor Hazardous Waste Combustor MACT Standards,Volume IV: Selection of MACT Standards andTechnologies, Chapeter 11, July 1999, for furtherdiscussion on how the maximum achievable controltechnologies were chosen for mercury.

standard provisions. At a minimum,your petition must include data orinformation which demonstrates thatyou meet the eligibility requirementsand that ensure you use MACT control,as defined in today’s rule.

Until the authorized regulatoryagency approves the provisions of thealternative standard in your petition (orestablishes other alternative standards)and until you submit a revised NOC thatincorporates the revised standards, youmay not operate under your alternativestandards in lieu of the applicableemission standards found in §§ 63.1204and 63.1205. We recommend that yousubmit a petition well in advance ofyour scheduled comprehensiveperformance test, perhaps including thepetition together with yourcomprehensive performance test plan.You may need to submit this petition inphases to ultimately receive approval tooperate pursuant to the alternativestandard provisions, similar to thereview process associated withperformance test workplans andperformance test reports. After initialapproval, alternative standard petitionsshould be resubmitted every five yearsfor review and approval, concurrentwith subsequent future comprehensiveperformance tests, and should containall pertinent information discussedabove.

You may find it necessary to completeany testing associated withdocumenting your eligibilityrequirements prior to yourcomprehensive performance test todetermine if in fact you are eligible forthis alternative standard, or you maychoose to conduct this testing at thesame time you conduct yourcomprehensive performance test. Thisshould be determined on a site-specificbasis, and will require coordinationwith the Administrator orAdministrator’s designee.

2. What Special Provisions Exist for anAlternative Mercury Standard for Kilns?

See § 63.1206(b)(10) and (11).a. What Happens if Mercury Is

Historically Not Present at DetectibleLevels? Situations may exist in which akiln cannot comply with the mercurystandard pursuant to the provisions in§ 63.1207(m) when using MACT controland when mercury is not present in theraw material at detectable levels.267 As

a result, today’s rule provides a petitionprocess for an alternative mercurystandard which only requirescompliance with a hazardous wastemercury feedrate limitation, providedthat historically mercury not beenpresent in the raw material at detectablelevels.

We received comments from thelightweight aggregate kiln industryexpressing concern with the stringencyof the mercury standard. Commentersoppose stringent mercury standards, inpart, because of the difficulty ofcomplying with day-to-day mercuryfeedrate limits. One potential problemcited pertains to raw material mercurydetection limits. Commenters point outthat if a kiln assumed mercury ispresent in the raw material at thedetection limit, the resulting calculateduncontrolled mercury emissionconcentration could exceed, or be asignificant percentage of, the mercuryemission standard. This may prevent akiln from complying with the mercuryemission standard pursuant to theprovisions of § 63.1207(m), even thoughMACT control was used.

We agree with commenters that this isa potential problem. In addition, it isnot appropriate to implement a mercurystandard compliance scheme that isrelatively more burdensome for kilnswith no mercury present in rawmaterial, as compared to kilns with highlevels of mercury in their rawmaterial.268 Because we establishprovisions that provide alternatives tokilns with high levels of mercury in theraw material, we are doing the same forthose kilns which do not have mercurypresent in raw material at detectablelevels.

b. What Are the Alternative StandardEligibility Requirements? To be eligiblefor this alternative mercury standard,you must submit data or informationwhich demonstrates that historicallymercury has not been present in yourraw material at detectable levels. You donot need to show that mercury hasnever been present at detectable levels.The determination of whether your dataand information sufficientlydemonstrate that mercury has not

historically been present in your rawmaterial at detectable levels will bemade on a site-specific basis. To assistin this determination, you also shouldprovide information that describes theanalytical methods (and their associateddetection limits) used to measuremercury in the raw material, togetherwith information describing howfrequently you measured raw materialmercury content.

If you are granted this alternativestandard, you will not be required tomonitor mercury content in your rawmaterial for compliance purposes.However, after initial approval, thisalternative standard must be reapprovedevery five years (see discussion below).Therefore, you should develop a rawmaterial mercury sampling and analysisprogram that can be used in futurealternative mercury standard petitionrequests for the purpose ofdemonstrating that mercury has nothistorically been present in raw materialat detectable levels.

c. What Is the Format of AlternativeMercury Standard? The alternativestandard requires you to use MACTcontrol for mercury (i.e., the level ofhazardous waste feedrate controlspecified in today’s rule). Thisalternative standard for mercury isconceptually identical to the emissionstandards in this final rule, because itrequires the use of an equivalent levelof hazardous air pollutant MACTcontrol as compared to the MACTcontrol used to determine the emissionstandards.

The mercury feedrate control levelwill differ for new and existing sources,and will differ for cement kilns andlightweight aggregate kilns. See§ 63.1206(b) (10) and (11) for a list of themercury hazardous waste feedratecontrol levels for purposes of thisalternative standard.269

d. What Is the Process for TheAlternative Mercury Standard Petition?If you are seeking this alternativemercury standard, you must submit apetition request to the Administratorthat includes the required informationdiscussed above. You will not beallowed to operate under this alternativestandard, in lieu of the applicableemission standards found in §§ 63.1204and 63.1205, unless and until theAdministrator approves the provisionsof this alternative standard and untilyou submit a revised NOC thatincorporates this alternative standard.



We recommend that you submit thesepetitions well in advance of yourscheduled comprehensive performancetest, perhaps including the petitiontogether with your comprehensiveperformance test plan. After initialapproval, alternative standard petitionsshould be resubmitted every five yearsfor review and approval, concurrentwith subsequent future comprehensiveperformance tests, and should containall pertinent information discussedabove.

B. Under What Conditions Can thePerformance Testing Requirements BeWaived? See § 63.1207(m).

In the April 1996 NPRM, we proposeda waiver of performance testingrequirements for sources that feed lowlevels of mercury, semivolatile metal,low volatile metal, or chlorine (see 61FR at 17447). Under the proposedwaiver, a source would be required toassume that all mercury, semivolatilemetal, low volatile metal, or chlorine(dependent on which hazardous airpollutant(s) the source wishes topetition for a waiver) fed to thecombustion unit, for all feedstreams, isemitted from the stack. The source alsowould need to show that theseuncontrolled emission concentrationsdo not exceed the associated emissionstandards, taking into considerationstack gas flow rate. The aboverequirements would apply for allperiods that a source elects to operateunder this waiver and for which thesource is subject to the requirements ofthis rulemaking. All comments receivedon this topic support this approach, andno commenters suggest alternativeprocedures to implement this provision.Today’s rule finalizes the proposedperformance test waiver provision, withone minor change expected to provideindustry with greater flexibility whendemonstrating compliance withoutcompromising protectiveness.

1. How Is This Waiver Implemented?The April 1996 proposal identified

two implementation methods todocument compliance with this waiverprovision. In today’s rule we finalizeboth proposed methods and add anotherimplementation method to providegreater flexibility when demonstratingcompliance with the provisions of thisperformance test waiver. As proposed,the first approach allows establishmentand continuous compliance with onemaximum total feedstream feedratelimit for mercury, semivolatile metal,low volatile metal, or chlorine and oneminimum stack gas flow rate. Thecombined maximum feedrate andminimum stack gas flow rate must result

in uncontrolled emissions below theapplicable mercury, semivolatile metal,low volatile metal, or chlorine emissionstandards. Both limits would becomplied with continuously; anyexceedance would require the initiationof an automatic waste feed cut-off.

Also as proposed, the secondapproach accommodates operationunder different ranges of stack gas flowrates and/or metal and chlorinefeedrates. Today’s rule allowsestablishment of different modes ofoperation with corresponding minimumstack gas flow rate limits and maximumfeedrates for metals or chlorine. If youuse this approach, you must clearlyidentify in the operating record whichoperating mode is in effect at all times,and you must properly adjust yourautomatic waste feed cutoff levelsaccordingly.

The third approach, which is anoutgrowth of our proposed approaches,allows continuous calculation ofuncontrolled stack gas emissions,assuming all metals or chlorine fed tocombustion unit are emitted out thestack. If you use this approach, youmust record these calculated values andcomply with the mercury, semivolatilemetal, low volatile metal, or chlorineemission standards on a continuousbasis. This approach provides greateroperational flexibility, but increasesrecordkeeping since the uncontrolledemission level must be continuouslyrecorded and included in the operatingrecord for compliance purposes.

If you claim this waiver provision,you must, in your performance testworkplan, document your intent to usethis provision and explain whichimplementation approach is used. Otherthan those limits required by thisprovision, you will not be required toestablish or comply with operatingparameter limits associated with themetals or chlorine for which the waiveris claimed. Your NOC also must specifywhich implementation method is used.The NOC must incorporate theminimum stack gas flowrate andmaximum metal and chlorine feedrateas operating parameter limits, or includea statement which specifies that youwill comply with emission standard(s)by continuously recording youruncontrolled metal and chlorineemission rate.

If you cannot continuously monitorstack gas flow rate, for the purpose ofdemonstrating compliance with theprovisions of this waiver, you may usean appropriate surrogate in place ofstack gas flow rate (e.g., cement kilnproduction rate). However, if you use asurrogate, you must provide in yourperformance test workplan data that

clearly and reasonably correlates thesurrogate parameter to stack gas flowrate.

2. How Are Detection Limits HandledUnder This Provision?

We did not address in April 1996NPRM how nondetect metal andchlorine feedstream results are handledwhen demonstrating compliance withthe feedrate limits or when calculatinguncontrolled emission concentrationsunder this provision. Commenterslikewise did not offer suggestions ofhow to handle nondetect data for thisprovision. After careful consideration,for the purposes of this waiver, werequire that you must assume that themetals and chlorine are present at thefull detection limit value when theanalysis determines the metals andchlorine are not detected in thefeedstream (except as described in thefollowing paragraph). Becauseperformance testing is waived underthis provision, it is appropriate to adopta more conservative assumption thatmetals and chlorine are present at thefull detection limit for the purposes ofthis waiver. (In other portions of today’srule we make the assumption that 50percent presence is appropriate giventhe different context involved).Assuming full detection limits providesan additional level of assurance thatresulting emissions still reflect MACTand do not pose a threat to humanhealth and the environment. If youcannot demonstrate compliance withthe provisions of this waiver whenassuming full detection limits, then youshould not claim this waiver and shouldconduct emissions testing todemonstrate compliance with theemission standard.

Based on the comments and asdiscussed in the previous section(Section A.2.a), we conclude it is notappropriate, for purposes of thisperformance test waiver provision, torequire a kiln to assume mercury ispresent at the full detection limit in itsraw material when the feedstreamanalysis determines mercury is notpresent at detectable levels. As a result,we allow kilns to assume mercury ispresent at one-half the detection limit inraw materials when demonstratingcompliance with the performance testwaiver provisions whenever the rawmaterial feedstream analysis determinesthat mercury is not present at detectablelevels.

C. What Other Waiver Was Proposed,But Not Adopted?

Waiver of the Mercury, SemivolatileMetal, Low Volatile Metal, or ChlorineStandard



270 Ancillary performance testing, monitoring,notification, record keeping, and reportingrequirements.

We proposed not to subject sources toone or more of the mercury, semivolatilemetal, low volatile metal, or chlorineemission standards (and otherrequirements) 270 if their feedstreams didnot contain detectable levels of thatassociated metal or chlorine (e.g., iftheir feedstreams did not contain adetectable level of chlorine, thehydrochloric acid/chlorine gas standardwould be waived—see 61 FR at 17447).As part of this waiver, a feedstreamsampling and analysis plan would bedeveloped and implemented todocument that feedstreams did notcontain detectable levels of the metalsor chlorine.

Several commenters supported thiswaiver, stating that it is of no benefit tohuman health or the environment torequire performance testing, monitoring,notification, and record-keeping ofconstituents not fed to the combustionunit. However, commenters weredivided in their support of the need toset minimum feedstream detectionlimits. Those supporting specifieddetection limits wrote that detectionlimits are needed to ensure thatappropriate analytical procedures areused and needed to provide consistencybetween sources. Those opposingspecified detection limits believed thatdetection limits are highly dependenton feedstream matrices. Therefore, toimpose a detection limit that applies toall sources and all feedstreams wouldnot be practicable. One commenterquestioned basing this waiver onnondetect values because a feedstreamanalyses that detects, at any time, aquantity of the metal or chlorine justabove the detection limit may beconsidered to be out of compliance.

We agree that little or noenvironmental benefit may be gained byrequiring performance testing,monitoring, notification, and recordkeeping for a constituent not fed to thecombustion unit. However, based on ourcareful analysis of comments and on ourreevaluation of the practicalimplementation issue inherent in thistype of waiver, we find that it may notalways be practicable to use detectionlimits to determine if a waste does ordoes not contain metals or chlorine. Weare concerned that facility-specificdetection limits may vary, from sourceto source, at levels such that sourceswith detection limits in the high-end ofthe distribution (due to their complexwaste matrix) have the potential forsignificant metal or chlorine emissions.Under the facility-specific detection

limit approach, a high-end detectionlimit source with relatively highemissions could qualify for the waiver;however, a source with a simplerfeedstream matrix with significantlylower amounts of metals in thefeedstream (but just above the detectionlimit) would not qualify. This not onlyturns the potential benefit of a waiverprovision on its head, but raises seriousquestions of national consistency,fairness, and evenness of environmentalprotection to surrounding communities.We also conclude that it is impracticalto set one common detection limit foreach hazardous air pollutant as part ofthis waiver because, as commentersstated, detection limits are matrixdependent.

Due to these issues, we were unableto devise an implementable andacceptable nondetect waiver provision,and therefore do not adopt one intoday’s final rule. As is described in theprevious section (Section B), however,we do provide a waiver of performancetesting requirements to sources that feedlow levels of mercury, semivolatilemetal, low volatile metal, or chlorine.Although this waiver provision does notwaive the emission standard,monitoring, notification, recordkeeping,and reporting requirements, it doeswaive emission tests and compliancewith operating parameter limits for theassociated metals or chlorine.

D. What Equivalency DeterminationsWere Considered, But Not Adopted?

In response to comments we receivedfrom the April 1996 NPRM, we includedin the May 1997 NODA a discussion ofan allowance of a one-time compliancedemonstration for hydrocarbon andcarbon monoxide at cement kilnsequipped with temporary midkilnsampling locations. (See 62 FR 24239.)This equivalency determinationrequired that alternative, continuouslymonitored, operating parameters beused in lieu of continuous monitoring ofhydrocarbon/carbon monoxide. Asdiscussed below, we conclude that theshortcomings associated with theproposed alternative operatingparameters created sufficientuncertainties, for implementation andoverall environmental protection, thatwe are not adopting an equivalencydetermination option in thisrulemaking. However, cement kilnshave the opportunity to petition theAdministrator under § 63.8(f) and63.1209(g)(1) to make a site-specific casefor this type of equivalencydetermination.

In response to the April 1996 NPRM,we received comments indicating thatsome kilns would need to either operate

at inefficient back-end temperatures (tooxidize hydrocarbons desorbed from theraw material) or be required to installand maintain a midkiln samplingsystem to demonstrate compliance withthe hydrocarbon/carbon monoxidestandards. Commenters believe that thismay not be feasible for some kilnsbecause: (1) Raising back endtemperatures may increase dioxinformation; (2) most long kilns are notequipped to sample emissions at themidkiln location; (3) costs associatedwith retrofit and maintenance may beconsidered high; and (4) maintenanceproblems associated with the samplingduct are difficult to overcome.

We received numerous comments onthe proposed hydrocarbon/carbonmonoxide equivalency approachdescribed in the May 1997 NODA. Manycement kilns support the option anddefend the use of alternative operatingparameters in lieu of continuous carbonmonoxide and hydrocarbon monitors.Many commenters oppose using anyparameters other than carbon monoxideor hydrocarbon as a combustionefficiency indicator and as surrogateemission standards for the nondioxinorganic hazardous air pollutants. Wehave found that a number of factorssuggest that a special provision allowinguse of alternative operating parameters,in lieu of carbon monoxide and/orhydrocarbon, is neither necessary norappropriate to include in thisrulemaking.

The alternative operating parametersassociated with a one-timedemonstration would have to assurethat compliance with the carbonmonoxide/hydrocarbon standard ismaintained at the midkiln location on acontinuous basis. We consideredadopting several different operatingparameters in lieu of hydrocarbon/carbon monoxide monitoring to achievethis goal. Maximum production rate wasconsidered as a continuous residencetime indicator. Minimum combustionzone temperature, continuouslymonitored destruction and removalefficiency using sulphur hexafluoride,and minimum effluent NOX limits werealso examined to ensure adequatetemperature is continuously maintainedin the combustion zone. To ensureadequate turbulence, we consideredusing minimum kiln effluent oxygenconcentration. Commenters did notsuggest additional alternative operatingparameters.

Each of these operating parametershave potential shortcomings, and we arenot convinced that use of theseparameters, even in combination,provides a combustion efficiencyindicator as reliable as continuous



271 An oxygen deficient zone in the kiln due toinadequate mixing, which could potentially resultin the emission of significant amounts of carbonmonoxide and organic hazardous air pollutants,could be well mixed with excess air by the time itreaches the kiln exit, where oxygen is monitored.Thus the oxygen monitor may not record anyoxygen concentration change and would not serveas an adequate control to ensure proper combustionturbulence.

272 We do not have, nor did commenters submit,data which show whether effluent kiln oxygenconcentration adequately correlates with carbonmonoxide/hydrocarbon produced from oxygendeficient zones in the kiln.

273 See Part Five, Section VII.D.(2)(b)(iii), forfurther discussion on combustion zone temperaturemeasurements.

274 Hydrofluoric acid, a CAA hazardous airpollutant, is a possible combustion byproduct ofsulphur hexafluoride.

275 This does not apply to the hydrocarbon andcarbon monoxide standard. See discussion in PartFour, Section VII.D on hydrocarbon and carbonmonoxide standards for cement kilns.

hydrocarbon/carbon monoxidemonitoring. We have identified thefollowing potential problems with thesealternative operating parameters: (1)Effluent kiln oxygen concentration maynot correlate well to carbon monoxide/hydrocarbon produced from oxygendeficient zones in the kiln; 271,272 (2)pyrometers, or other temperaturemonitoring systems, may not providedirect and reliable measurements ofcombustion zone temperature; 273 (3)some combustion products of sulphurhexaflouride are toxic and regulatedhazardous air pollutants; 274 (4) there areno demonstrated performancespecifications for continuous sulphurhexaflouride monitors; and (5) it iscontrary to other air emissionlimitations (in principle) to requireminimum (not maximum) NOX limits.

On balance, the lack of adequatedocumentation allowing us to resolvethese uncertainties and potentialproblem areas prevents us from furtherconsidering this type of hydrocarbon/carbon monoxide equivalencydetermination provision for inclusion intoday’s final rule. As stated above,however, cement kilns have theopportunity to petition theAdministrator under § 63.8(f) to make asite-specific case for this type ofequivalency determination.

As is explained in Part Four, SectionVII.C(9)(c), today’s rulemaking subjectsnewly constructed hazardous wasteburning cement kilns at greenfield sitesto a main stack hydrocarbon standard ofeither 20 or 50 ppmv. We clarify thatthis standard applies to these sourceseven if they applied and receivedapproval for an alternative monitoringapproach described above, because theintent of this hydrocarbon standard is tocontrol organic hazardous air pollutantsdesorbed from raw material and not tocontrol combustion efficiency.

E. What are the Special ComplianceProvisions and Performance TestingRequirements for Cement Kilns with In-line Raw Mills and Dual Stacks?

Preheater/precalciner cement kilnswith dual stacks and cement kilns within-line raw mills require specialcompliance provisions and performancetesting requirements because they areunique in design.

Preheater/precalciner kilns with dualstacks have two separate air pollutioncontrol systems. As discussed in SectionF below, emission characteristics fromthese separate stacks could be different.As a result, these kilns must conductemission testing in both stacks todocument compliance with theemission standards 275 and mustestablish separate operating parameterlimits for each air pollution controldevice. See § 63.1204(e)(1).

Cement kilns with in-line raw millseither operate with the raw mill on-lineor with the raw mill off-line. Asdiscussed in Section F below, these twodifferent modes of operation could havedifferent emission characteristics. As aresult, cement kilns with in-line rawmills must conduct emission testingwhen the raw mill is off-line and whenthe raw mill is on-line to documentcompliance with the emission standardsand must establish separate operatingparameters for each mode of operation.These kilns must document in theoperating record each time they changefrom one mode of operation to thealternate mode. They must also begincalculating new rolling averages foroperating parameter limits and complywith the operating parameter limits forthat mode of operation, after theyofficially switch modes of operation. Ifthere is a transition period associatedwith changing modes of operation, thekiln operator has the discretion todetermine when, during this transition,the kiln has officially switched to thealternate mode of operation and when itmust begin complying with theoperating parameter limits for thatalternate mode of operation. See63.1204(d)(1).

Preheater/precalciner kilns with dualstacks that also have in-line raw millsdo not have to conduct dioxin/furantesting in the bypass stack todemonstrate compliance with thestandard when the raw mill is off-line.We have concluded that dioxin/furanemissions in the bypass stack are notdependent on the raw mill operatingstatus because dioxin/furan emissions

are primarily dependent on temperaturecontrol. A kiln may assume that whenthe raw mill is off-line, the dioxin/furanemissions in the bypass stack areidentical to the dioxin/furan emissionswhen the raw mill is on-line and maycomply with the bypass stack dioxin/furan raw mill on-line operatingparameters for both modes of operation.See § 63.1204(d)(1).

F. Is Emission Averaging Allowable forCement Kilns with Dual Stacks and In-line Raw Mills?

In the April 1996 NPRM, we did notsubdivide cement kilns by process typewhen setting emission standards (see 61FR at 17372–17373). As a result, wereceived many comments from thecement kiln industry indicating thatpreheater/precalciner cement kilns withdual stacks and cement kilns with in-line raw mills have unique design andoperating procedures that necessitatethe use of emission averaging whendemonstrating compliance with theemission standards. We addressed thesecomments in the May 1997 NODA bydiscussing an allowance for emissionaveraging (for all standards except forhydrocarbon/carbon monoxide) atpreheater/precalciner cement kilns withdual stacks when demonstratingcompliance with the emission standards(see 62 FR at 24240). We also discussedallowing cement kilns with in-line rawmills to demonstrate compliance withthe emission standards on a time-weighted average basis to account fordifferent emission characteristics whenthe raw mill is active as opposed towhen it is inactive. In light of thefavorable comments received, and thelack of significant concerns to thecontrary, we adopt these emissionaveraging provisions in today’s rule.

1. What Are the Emission AveragingProvisions for Cement Kilns with In-lineRaw Mills?

See § 63.1204(d).As explained in the May 1997 NODA,

emissions of hazardous air pollutantscan be different when the raw mill isactive versus periods of time when themill is out of service. We received manycomments on this issue, all in favor ofan emissions averaging approach toaccommodate these different modes ofoperation. As a result, we adopt aprovision that allows cement kilns thatoperate in-line raw mills to average theiremissions on a time-weighted basis toshow compliance with the metal andchlorine emission standards.

Emission averaging for in line rawmills will not be allowed when theydemonstrate compliance with thehydrocarbon/carbon monoxide standard



276 The Agency does not have, nor didcommenters submit, sufficient data to determinewhether emissions will be higher or lower when theraw mill is inactive.

277 Today’s rulemaking allows a hazardous wastesource, when not burning hazardous waste, toeither comply with the hazardous waste cementkiln MACT standards or the non hazardous wastecement kiln standards (see Part Five, Section I).

because hydrocarbon and carbonmonoxide are monitored continuallyand serve as a continuous indicator ofcombustion efficiency. No commenterstates that emission averaging is neededfor hydrocarbon/carbon monoxide.Emission averaging for particulatematter will not be allowed because thisstandard is based on the New SourcePerformance Standards found in § 60.60subpart F. We interpret these standardsto apply regardless if the raw mill is on

or off. (Note that this is consistent withthe proposed Nonhazardous WastePortland Cement Kiln Rule. See 56 FR14188). In addition, emission averagingfor dioxin/furan will not be allowedbecause cement kilns with in-line rawmills are expected to controltemperature during both modes ofoperation to comply with the standard.No commenter stated that emissionaveraging was needed for dioxin/furan.

a. What Is the AveragingMethodology? In the May 1997 NODA,we did not specify an averagingmethodology. As a result, commenterssuggested that the following equationwould adequately calculate the time-weighted average concentration of aregulated constituent when consideringthe length of time the in-line raw millis on-line and off-line:

C C T T T C T T Ttotal mill mill mill mill mill mill mill mill= ( ) × +( )( ){ } + ( ) × +( )( ){ }-off -off -off -on -on -on -off -on/ /

Where:Ctotal = time-weighted average

concentration of a regulatedconstituent considering both rawmill on time and off time.

Cmill-off = average performance testconcentration of regulatedconstituent with the raw mill off-line.

Cmill-on = average performance testconcentration of regulatedconstituent with the raw mill on-line.

Tmill-off = time when kiln gases are notrouted through the raw mill.

Tmill-on = time when kiln gases arerouted through the raw mill.

We agree that this equation properlycalculates the time-weighted averageconcentration of the regulatedconstituent when considering both rawmill operation and raw mill down timeand are adopting it in today’s rule.

b. What Is Required During EmissionTesting? As discussed, sources that usethis emission averaging provision mustconduct performance testing for bothmodes of operation (with the raw millboth on-line and off-line),demonstrating appropriate operatingparameters during both test conditions.One commenter suggests that theAgency allow sources to demonstrateboth raw mill on-line and off-lineoperations within the same test runs.This would allow a test under onecondition instead of two and would givemore flexibility by ensuring identicaloperating parameters for raw mill on-line operations as opposed to off-lineoperations. This also could theoreticallyresult in fewer automatic waste feedcutoffs when transitioning from onemode of operation to another. Althoughthis approach may have some benefit,we conclude that it is necessary todemonstrate, through separate emissiontesting, the comparison of emissionswhen operating with the raw mill on-line as opposed to the raw mill off-line.The separate emission testing is

necessary to demonstrate whetheremissions are higher or lower when theraw mill is not active to assurecompliance with the emission standardson a time-weighed basis.276

c. How Is Compliance Demonstrated?In the May 1997 NODA, we did notdiscuss specific compliance provisionsof an emission averaging approach.After careful consideration, however,we determine that to use this emissionaveraging provision, you mustdocument and demonstrate compliancewith the emission standards on anannual basis by using the aboveequation. Shorter averaging times wereconsidered, but were not chosen since itmay be difficult for a kiln with an in-line raw mill to comply with a shortaveraging period if the raw mill must beoff-line for an extended period of time.Therefore, you must annually documentin your operating record thatcompliance with the emission standardwas demonstrated for the previousyear’s operation by calculating yourestimated annual emissions with theabove equation. The one-year blockaverage begins on the day you submityour NOC. You must include allhazardous waste operations in that oneyear block period, and you also mustinclude all nonhazardous wasteoperations that you elect to comply withhazardous waste MACT standards,when demonstrating annualcompliance.277

d. What Notification Is Required?Again, in the May 1997 NODA, we didnot discuss specific notificationrequirements. After carefulconsideration, we determined that ifyou use this emission averaging

provision, you must notify theAdministrator of your intent to do so inyour performance test workplan. Severalcommenters favor allowing time-weighted emissions averaging, so longas historical data are submitted to justifyallowable time weighting factors(explained below). We agree with thesecomments and require that you submithistorical raw mill operation data inyour performance test workplan. Thesedata should be used to estimate thefuture down-time the raw mill willexperience. You must document in yourperformance test workplan thatestimated emissions and estimated rawmill down-time will not result in anexceedance of the emission standard onan annual basis. You also mustdocument in your NOC that theemission standard will not be exceededbased on the documented emissionsfrom the compliance test and predictedraw mill down-time.

2. What Emission Averaging Is Allowedfor Preheater or Preheater-PrecalcinerKilns with Dual Stacks? (See§ 63.1204(e).)

As explained in the May 1997 NODA,and in an earlier section of thispreamble (see Part Four, Section V.II.B),emissions of hazardous air pollutantscan be different in a preheater orpreheater-precalciner cement kiln’smain stack as opposed to the bypassstack. We received many comments onthis issue, all in favor of the emissionsaveraging approach discussed in theNODA to accommodate the differentemission characteristics in these stacks.Therefore, we today finalize a provisionto allow preheater or preheater-precalciner cement kilns with dualstacks to average emissions on a flow-weighted basis to demonstratecompliance with chlorine and metalemission standards.

Emission averaging to demonstratecompliance with the hydrocarbon/carbon monoxide standard is not



278 New kilns at greenfield locations must alsocomply with a main stack hydrocarbon standards.For these sources, emission averaging forhydrocarbons would not appropriate because the

purpose of the main stack hydrocarbon standard isto control organic hazardous air pollutants thatoriginate from the raw material.

279 See Final Rule, Burning of Hazardous Wastein Boilers and Industrial Furances, February 21,1991, 56 FR at 7158.

needed at preheater and preheater-precalciner cement kilns with dualstacks since today’s rule requires thesekilns to monitor hydrocarbon or carbonmonoxide in the bypass stack only.278

Emission averaging for particulatematter is no longer needed since theformat of the standard (0.15 kg/Mg dryfeed) implicitly requires the kiln toconsider mass emissions from both

stacks to demonstrate compliance withthe emission standard. In addition,emission averaging for dioxin/furan willnot be allowed because cement kilnswith dual stacks are expected to controltemperature in both air pollutioncontrol systems to comply with thestandard. No commenter stated thatemission averaging was needed fordioxin/furan.

a. What Is the Average Methodology?In the May 1997 NODA, we did notspecify an averaging methodology.However, commenters suggested thatthe following is an appropriate equationto calculate the flow-weighted averageconcentration of a regulated constituentwhen considering emissions from bothstacks:

C C Q Q Q C Q Q Qtot main main main bypass bypass bypass main bypass= ( ) × +( )( ){ } + ( ) × +( )( ){ }/ /

Where:Ctot = flow-weighted average

concentration of the regulatedconstituent

Cmain = average performance testconcentration demonstrated in themain stack

Cbypass = average performance testconcentration demonstrated in thebypass stack

Qmain = volumetric flowrate of mainstack effluent gas

Qbypass = volumetric flowrate of bypasseffluent gas

We agree that this equation properlycalculates the flow-weighted averageconcentration of the regulatedconstituent when considering emissionsfrom both stacks and it is adopted intoday’s rule.

b. What Emissions Testing andCompliance Demonstrations AreNecessary? To use this emissionaveraging provision, you mustsimultaneously conduct performancetesting in both stacks during yourcomprehensive performance test tocompare emission levels of theregulated constituents (as proposed).These emission data must be used asinputs to the above equation todemonstrate compliance with theemission standard.

You must develop operatingparameter limits, and incorporate theselimits into your NOC, that ensures youremission concentrations, as calculatedwith the above equation, do not exceedthe emission standards on a twelve-hourrolling average basis. These operatingparameters should limit the ratio of thebypass stack flowrate and combinedbypass and main stack flowrate suchthat the emission standard is compliedwith on a twelve-hour rolling averagebasis. Whereas this was not proposed,we conclude that this provision isnecessary to assure compliance with thestandards since the ratio of stack gas

flowrate and bypass stack flowratecould deviate from the levelsdemonstrated during the performancetest.

c. What Notification Is Required? Inthe May 1997 NODA, we did notdiscuss specific notificationrequirements. After carefulconsideration, however, we determinethat to use this emission averagingprovision, you must notify theAdministrator of your intent to do so inyour performance test workplan. Theperformance test workplan mustinclude, at a minimum, information thatdescribes your proposed operatinglimits. You must document your use ofthis emission averaging provision inyour NOC and document the results ofyour emissions averaging analysis afterestimating the flow weighted averageemissions with the above equation. Youmust also incorporate into the NOC theoperating limits that ensurescompliance with emission standards ona twelve-hour rolling average basis.

G. What Are the Special RegulatoryProvisions for Cement Kilns andLightweight Aggregate Kilns that FeedHazardous Waste at a Location OtherThan the End Where Products AreNormally Discharged and Where FuelsAre Normally Fired? (§ 63.1206(b)(12)and (b)(8)(ii))

As discussed in Part Four, SectionIV.B., the Agency is allowing you tocomply with either a carbon monoxideor hydrocarbon standard. However, wehave concluded that this option tocomply with either standard should notapply if you operate a cement kiln orlightweight aggregate kiln and feedhazardous waste at a location other thanthe end where products are normallydischarged and where fuels arenormally fired these other locationsinclude, at the mid kiln or the cold,upper end of the kiln. Consistent with

the Boilers and Industrial Furnaceregulations (see § 266.104(d)), we aretoday requiring you to comply with thehydrocarbon standard, and are notgiving you the option to comply withthe carbon monoxide standard, if youfeed hazardous waste in this manner.This is because we are concerned thathazardous waste could be fired into alocation such that nonmetal compoundsin the waste may be merely evaporatedor thermally cracked to form pyrolysisbyproducts rather than be completelycombusted.279 If this occurs, there is thepotential that little carbon monoxidewill be generated even thoughsignificant hydrocarbons are beingemitted. Carbon monoxide monitoringwould thus not ensure that organichazardous air pollutant emissions arebeing properly controlled. We do notanticipate this requirement to be overlyburdensome, since it is a currentrequirement of the Boilers andIndustrial Furnace regulation.

We have also concluded that it wouldnot be appropriate for you to complywith the hydrocarbon standard in thebypass duct if you operate a cement kilnand feed hazardous waste into alocation downstream of your bypasssampling location relative to flue gasflow direction. Such operation wouldresult in hazardous waste combustionthat would not be monitored by ahydrocarbon monitor. Today’srulemaking thus requires you to complywith the main stack hydrocarbonstandard of 20 ppmv if you feedhazardous waste in this manner. This isalso consistent with the Boilers andIndustrial Furnace regulations, whichdo not allow you to monitorhydrocarbons in the bypass duct if youoperate a short kiln and if you feedhazardous waste in the preheater orprecalciner (see § 266.104(f)(1)).

In addition to the above requirements,if you operate a cement kiln or



280 We do not require you to document that yourfeedstreams have de minimis mercury levels toqualify for this alternative standard becausemercury is a volatile metal and is generally notcontrolled with particulate matter controltechnologies.

281 As discussed in Part Four, Section VI.C.4.a,particulate matter floor control for hazardous wasteincinerators is defined as the use of either fabricfilters, electrostatic precipitators (dry or wet), orionizing wet scrubbers (sometimes in combinationwith venturi, packed bed, or spray tower scrubbers)that achieve particulate matter emission levels of0.015 gr/dscf or less.

282 See Final Technical Support Document,Volume 3, Chapter Four, July, 1999, for furtherdiscussion.

283 The cement kilns and lightweight aggregatekilns that are also covered by today’s final rule havefeedrates of metals far above any de minimisthreshold. See Final Technical Support Document,Volume 3, Chapter Four, July, 1999, for furtherdiscussion. Therefore, in light of the commentersrequesting alternative standards and in light of thefeedstream levels of metals going into the kilns, wehave elected to offer an alternative particulatematter standard only to incinerators.

lightweight aggregate kiln and feedhazardous waste at a location other thanthe end where products are normallydischarged and where fuels arenormally fired, you are also required todemonstrate compliance with thedestruction and removal efficiencystandard every five years as opposed toa one-time destruction and removaldemonstration We require you to do thisbecause the unique design andoperation of such a waste firing systemnecessitates a compliancedemonstration for this standard everyfive years (see previous discussion inpart Four, Section IV.A.3.).

H. What is the Alternative ParticulateMatter Standard for Incinerators? See§ 63.1206(b)(15).

As discussed in Part Four, SectionII.A.2, today’s rule establishes aparticulate matter standard of 0.015 gr/dscf for incinerators as a surrogate tocontrol nonenumerated metal hazardousair pollutants (i.e., antimony, cobalt,manganese, nickel, selenium). Ofcourse, particulate matter air pollutioncontrol devices also exert control onother metals (except highly volatilespecies such as mercury), including theenumerated metals. (The enumeratedmetal hazardous air pollutants are thoseCAA metal hazardous air pollutantsregulated directly via individualemission standards in today’s rule, i.e.,mercury, semivolatile metals, lowvolatile metals). A number ofcommenters, primarily incineratoroperators, assert that a particulatematter standard should not be used asa surrogate control for metals insituations where the particulate matterdoes not contain any metal hazardousair pollutants (i.e., situations when thewaste does not contain any metals,except perhaps mercury and theresulting ash contains only relativelybenign ash or soot). These commentersargue that the cost associated withreducing particulate matter levels below0.015 gr/dscf would be excessive andthat some type of alternative standard(reflecting superior metal feedratecontrol) be created.

After considering these comments andanother type of particulate mattercontrol technology, we conclude that itis appropriate to offer an alternativeparticulate matter standard of 0.03 gr/dscf for incinerators that have deminimis levels of hazardous airpollutant metals in their feedstreams,and we have adopted a petition processto allow incinerators to seek thisalternative standard. An alternativeparticulate matter standard is within thescope of our overall preamblediscussions of the control of particulate

matter and metal emissions, the ways inwhich the Agency was consideringfeedrate as part of its MACT analysis,our approaches to enumerated and non-enumerated CAA hazardous airpollutant metals, and the presentation ofoptions for compliance testing whenonly de minimis levels of metals arepresent.

1. Why is this Alternative ParticulateMatter Standard Appropriate underMACT?

An alternative particulate matter floorlevel of 0.030 gr/dscf is appropriate foran incinerator that can demonstrate ithas de minimis levels of CAA hazardousair pollutant metals (except mercury), asdefined below, in its feedstreams. Asdiscussed in other portions of thispreamble and in our technicalbackground documents for thisrulemaking, control of metals (otherthan mercury) is a function, in apractical sense, of both the feedrate ofthose metals into the combustion deviceas well as the design, operation, andmaintenance of a source’s air pollutioncontrol devices for particulate matter.Given the intertwined relationshipbetween these two factors, the Agencyhas concluded that a particulate matterfloor control level of 0.015 gr/dscf is notwarranted for sources using superiorfeedrate control (i.e. beyond MACT) toreduce metal emissions, which in thiscase would be shown by having non-detectable levels of metals in theirfeedstreams (discussed in more detailbelow).280

We also conclude that the floorcontrol for this alternative standard isthe use of a venturi scrubber or the useof the same, but less sophisticated,particulate matter control technologiesthat were established for the 0.015 gr/dscf standard.281 These floortechnologies, including venturiscrubbers, were the basis of ourparticulate matter floor standard of0.029 gr/dscf which was published forcomment in the May 1997 NODA. See62 FR at 24221. Although we have sincedetermined that 0.015 gr/dscf is atechnically achievable and appropriateMACT floor control level for

incinerators based on a suite oftechnologies that does not includeventuri scrubbers, we conclude that analternative floor level of 0.030 gr/dscfthat includes venturi scrubbers in thefloor is appropriate for sources usingsuperior metal feedrate control. Putanother way, we view the average of the12 percent best performing incineratorsas including incinerators with venturiscrubbers when the incinerator isexercising beyond-MACT feed control ofhazardous air pollutant metals.282 Wealso note that the final rule for medicalwaste incinerators establishes aparticulate matter standard of 0.030 gr/dscf for medium sized existing sourcesand small new sources that is based onmedium efficiency venturi scrubbers.See 62 FR at 48348. The alternative floorlevel of 0.030 gr/dscf that is adopted inthis final rulemaking is appropriatewhen we include venturi scrubbers asan alternative floor control technologywhen superior feed rate control is beingemployed.283

Particulate matter control below 0.030gr/dscf is still necessary to control metalemissions at sources with de minimislevels of hazardous air pollutant metalsin their feedstreams for several reasons.Even if an incinerator obtains non-detect analytical results for one or moremetals in its feedstream, this does notconclusively prove that metals areabsent. Rather, all that such laboratoryresults mean is that the metals are notcontained in the feedstream above thedetection limit used in the analysis.This detection limit may be low but itcan also be fairly high depending on thewaste matrix. As previously discussedin Part Five, Section X.C.1, commentershave indicated that feedstream metaldetection limits are highly dependenton the feedstream matrix.

Given that our prerequisite for thealternative standard is that de minimislevels of metals are present, we musttake into account this phenomenon ofmatrix-dependent detection limits. Weare unwilling simply to allow facilitiesupon a showing of non-detectable levelsof metals to avoid particulate mattercontrols entirely, especially given thecomplementary controls in practiceprovided by both feedrate control and



284 See also CAA section 112(n)(7) (requirementsof section 112 should be consistent with those ofRCRA Subtitle C to the maximum extentpracticable).

particulate matter air pollution controldevices. On the other hand, it would beoverly narrow to give essentially nocredit for superior feedrate control(shown by non-detectable levels ofmetals) by requiring these incineratorsto meet 0.015 gr/dscf. It appears,therefore, to be an appropriate balanceto allow facilities with non-detectablelevels of metals (other than mercury) tomeet a standard of 0.030 gr/dscf. Thiswill assure control reflectingperformance of the best performingplants that use superior (i.e., beyondMACT) feedrate control, especially inthe event that detection limits for aparticular waste matrix are unusuallyhigh. Because we are moving to aPerformance Based MeasurementSystem (PBMS) we cannot rely uponpreviously approved EPA standardmethods as a means to predict detectionlevels in various matrices. Therefore, weare retaining a particulate matterstandard 0.030 gr/dscf to offset thepotential for high detection limits.

2. How Do I Demonstrate Eligibility forthe Alternative Standard?

Although we adopt a particulatematter standard as a surrogate to controlnonenumerated metal hazardous airpollutants, particulate matter control isan integral part of the semivolatile andlow volatile metal emission standards aswell, as discussed above. See Part Four,Section II.A.1, for further discussion.We therefore conclude that you mustdocument that not only thenonenumerated metals meet the deminimis criteria explained below, butthat the semivolatile and low volatilemetals do as well. This providesassurance that superior feedrate controlis being achieved for all hazardous airpollutant metals, which in turn allowsus to provide you with the opportunityto use the alternative particulate matterstandard.

To demonstrate eligibility, you mustdocument that you meet twoqualification requirements. First, youmust document that your feedstreamsdo not contain detectable levels of CAAhazardous air pollutant metals, apartfrom mercury (i.e., antimony, cobalt,manganese, nickel, selenium, lead,cadmium, chromium, arsenic andberyllium). This requirement isnecessary to ensure that you have deminimis levels of metals in yourfeedstreams, and assures us that you areusing superior feedrate control. Youmust conduct feedstream analyses atleast annually to document that yourfeedstreams do not contain detectablelevels of these metals. Permittingofficials may, on a site-specific basis,require more frequent feedstream

analyses to better ensure that youcomply with this eligibilityrequirement.

Second, you must document that yourcalculated uncontrolled metalemissions, i.e., no system removalefficiency, are below the numericalsemivolatile and low volatile metalemission standards. When calculatingthese uncontrolled emissions, you mustassume metals are present at one-halfthe detection limit and are categorizedinto their appropriate volatilitygrouping for purposes of thisrequirement. The one-half detectionlimit assumption provides a relatively,but not overly, conservative wayassuring that de minimis determinationsare not given to sources with very highdetection limits.

For example, the combineduncontrolled emissions for lead,cadmium and selenium, when assumingthese metals are present at one-half thedetection limit, must be below 240 µg/dscm. The combined uncontrolledemissions for antimony, cobalt,manganese, nickel, chromium, arsenicand beryllium, when assuming thesemetals are present at one-half thedetection limit, must be below 97 µg/dscm. We require this second eligibilityrequirement because (1) it ensures youhave de minimis levels of metals in yourfeedstreams even though metals can bepresent at levels below the detectionlimit, and (2) it encourages you to obtainreasonable detection limits.

3. What Is the Process for theAlternative Standard Petition?

If you are seeking this alternativeparticulate matter standard, you mustsubmit a petition request to theAdministrator, or authorized regulatoryAgency, that includes thedocumentation discussed above. Youwill not be allowed to operate underthis alternative standard until theAdministrator determines that you meetthe above qualification requirements.Although we are not requiring that youinclude this petition as part of thecomprehensive performance testworkplan, we strongly recommend thatyou do so. This approach has severaladvantages: (1) It will clarify which PMstandard you are complying with as ofyour documentation of compliance, andavoid potential confusion about yourstate of compliance; (2) it will helpensure that the planned performancetests cover all of the relevant parametersand standards and will facilitateinterpretation of performance testresults; (3) it will help avoid costs ofhaving to conduct a separateperformance test to show compliancewith the alternative standard, which

would include re-testing and re-establishment of many of the sameparameters as would be covered in theinitial comprehensive performance test;and (4) it will help maximize the timethat the regulatory agency needs toevaluate your demonstration of theprerequisite, non-detect levels of metalsin your feed, including the time neededfor you to respond to any additionalinformation that may be requested bythe agency. Agency approval of acomprehensive performance testworkplan that also includes this petitionrequest will be deemed as approval foryou to operate pursuant to thisalternative standard. In ourimplementation of today’s final rule, wewill address as appropriate variousconsiderations related to processingthese petitions, including the timing ofthe submittal, review and approval. Wefully expect that Agency permit officialswill act expeditiously on these petitionsso that both the source and thereviewing official know what particulatematter level the comprehensiveperformance test must show is beingachieved.

XI. What Are the PermittingRequirements for Sources Subject to thisRule?

As indicated in Part One, we intendthe requirements of this rule to meet ourobligations for hazardous wastecombustor air emission standards undertwo environmental statutes, the CleanAir Act and the Resource Conservationand Recovery Act. The overlapping airemission requirements of these twostatutes have historically resulted insome duplication of effort. Indeveloping a permitting scheme thataccommodates the requirements of bothstatutes, with regard to the new airemissions limitations and standardsbeing promulgated in this rule, our goalis to avoid any such duplication to theextent possible. This goal is consistentwith the RCRA statutory directive ofsection 1006(b)(1) to ‘‘integrate allprovisions of (RCRA) for purposes ofadministration and enforcement and(* * *) avoid duplication, to themaximum extent practicable, with theappropriate provisions of the Clean AirAct.’’ 284 It also is consistent with ourobjectives to streamline requirementsand follow principles that promote‘‘good government.’’



285 When referring to permitting under the CAA,we mean operating permits under title V of theCAA. The regulations governing state and federaltitle V permit programs are codified in 40 CFR parts70 and 71, respectively.

286 The possibility of issuing only one EPA permitunder either CAA or RCRA authority, and theensuing legal barriers rendering that approachinfeasible, also were discussed in the preamble forthe proposed rule (61 FR 17451, April 19, 1996).

A. What Is the Approach to Permittingin this Rule?

1. In General What Was Proposed andWhat Was Commenters’ Reaction?

In the April 1996 NPRM, we proposedplacing the MACT air emissionsstandards in the CAA regulations at 40CFR part 63 and proposed to referencethe standards in the RCRA regulations at40 CFR parts 264 and 266. (see 61 FR17451, April 19, 1996). At that time, webelieved that placing the standards inboth the CAA and RCRA regulationswould provide maximum flexibility toregulatory authorities at the Regional,State, or local levels to coordinatepermitting and enforcement activities inthe manner most appropriate for theirindividual circumstances.285 We alsobelieved that this approach wouldalleviate the potential for duplicativerequirements across permittingprograms.

In addition, we presented twoexamples of ways for permittinghazardous waste combustors subject tothe new MACT standards. Theseexamples reflected, in part, theproposed approach of incorporating thenew MACT standards into both RCRAand CAA implementing regulations.286

(See 61 FR 17451, April 19, 1996.) In thefirst example, the two permittingprograms would work together to issueone permit, under joint CAA and RCRAauthority, that would meet all therequirements of both programs. In thesecond example, the two permittingprograms would coordinate their effortswith each program issuing a separatepermit; the items common to both (e.g.,the air emissions standards) would beincluded in one permit andincorporated by reference into the otherpermit.

Comments on the April 1996 NPRMexpressed widespread support forproviding flexibility for regulatoryagencies to implement common sensepermitting schemes that fit theirorganization and resources. However,commenters disagreed as to whichapproach would best provide suchflexibility. A few commenters thoughtthat the April 1996 NPRM approach,placing the standards in both CAA andRCRA regulations, would both provideflexibility to choose which program

would issue permits and therefore avoidduplication.

On the other hand, we receivedseveral comments challenging ourassumption that placement of thestandards in both CAA and RCRAregulations would optimize flexibilityfor regulatory agencies. Thesecommenters believed that the regulatoryagencies would be, in fact, more limited.They noted that both the RCRA andCAA programs would be responsible forincorporating the standards, to someextent, into their permits, even if just byreferencing the other. Commenters alsowere concerned with the potential forconflicting conditions between the twopermits, particularly with regard totesting, monitoring, and certificationrequirements. In addition, they felt thatthe conditions common to both permitsmight be subject to separate decision-making processes. For example, theymight potentially be subject to twodifferent administrative or judicialappeals procedures and two permitmodification procedures. If thishappened, the Agency would notachieve its stated objective of avoidingduplication between the two programs.Additionally, our example pointing toclose coordination between programs toavoid duplication was countered bycommenters examples where suchcoordination has not occurred, eitherdue to logistical problems withinregulatory agencies or to differences inadministrative processes between thetwo programs.

Commenters also expressed concernabout the potential for enforcement ofthe same requirement under twodifferent statutes that they believed theproposed approach would create. Sincethe requirements would have to beincorporated into both RCRA permitsand CAA title V permits, sources wouldhave to comply with both. Although westated in the proposal that we did notexpect to take enforcement action underboth permits (see 62 FR 17452),commenters noted that this would notrestrain State or local authorities frominitiating dual enforcement actions. Inaddition, commenters pointed out thatthey would be vulnerable to citizensuits under both statutes.

The majority of the commentersvoiced a desire for the Agency to avoidduplicate requirements or redundantprocesses. We received severalsuggestions for alternative approaches,which can be grouped in three ways: (1)Requiring regulatory agencies todevelop a separate permitting programto cover elements common to both CAAand RCRA (i.e., air emissions andrelated operating requirements) whilemaintaining separate permits for the

other elements; (2) Developing a singlemulti-media permit to cover all RCRAand CAA requirements applicable tohazardous waste combustors; and (3)placing the standards only in CAAregulations and incorporation only intothe title V permits.

The first alternative, i.e., requiring aseparate permitting program for airemissions and related parameters, is avery different approach that wouldlikely require the development of morenew regulations. However, duplicationmay be avoided without promulgationof an ‘‘independent’’ permitting schemejust for the elements common to bothRCRA and CAA programs. Otheralternatives would not involve the timeand effort needed to craft and adopt anew regulatory scheme, such as thatsuggested.

We believe that the secondalternative, pursuing multi-mediapermits, had some merit. Ascommenters pointed out, the Agency’sPermits Improvement Team expressedsupport for multimedia permits in its‘‘Concept Paper.’’ The PermitsImprovement Team also acknowledged,however, that true multimedia permitshave been difficult to develop. We stillsupport multimedia permitting, and thisrule does not preclude this approach.Nevertheless, we do not believe that, atthis point, we can rely on multimediapermitting as an overall approach toimplementing this rule. Some Stateshave successfully piloted multi-mediapermitting or implemented ‘‘one-stop’’permits that address both RCRA andCAA requirements. We encourage Statesto continue these efforts and to applythem to hazardous waste combustorpermitting to the extent possible. Evenfor States that do not currently pursuemultimedia or one-stop permits, thisrule presents unique opportunities tostart moving in that direction.

The third alternative had a couple ofvariations. The straightforward versionwas simply to place the MACT airemission standards in the CAAregulations, incorporate them into titleV permits, and continue to issue RCRApermits for other RCRA-regulatedaspects of the combustion unit, as wellas of the rest of the facility (e.g.,corrective action, general facilitystandards, other combustor-specificconcerns such as materials handling,risk-based emissions limits andoperating requirements, as appropriate,and other hazardous waste managementunits). A variation of this was todevelop a RCRA permit-by-ruleprovision to defer to title V permits. Thestraightforward approach was favoredby the majority of the commenters.Some offered, as further support for this



287 As discussed earlier, states may be able todevelop combined permits that address both RCRAand CAA requirements. Such permits would haveto cite the appropriate authority (CAA or RCRA) foreach condition, and have to be signed by theappropriate officials of each program. Permitconditions would continue to be enforced undertheir respective authorities as well.

288 Although CAA section 112(n)(7) is directed atharmonizing requirements with RCRA, it does notprovide a jurisdictional basis for deferral (i.e.,nonpromulgation of mandated section 112(d)MACT standards in light of the existence of RCRAstandards).

position, a reference to therecommendation put forth by the PermitImprovement Team’s Alternatives toIndividual Permits Task Force thatcalled for permitting air emissions fromhazardous waste combustors under theCAA. The variation of developing aRCRA permit-by-rule provision is not asresponsive to commenters’ concernsbecause, among other things, thatapproach would not avoid the potentialfor dual enforcement. Although thepermit-by-rule has the effect of deferringto the title V permit, the facility is stillconsidered to have a RCRA permit forthe combustor’s air emissions.

2. What Permitting Approach IsAdopted in Today’s Rule?

We found the arguments for thestraightforward approach (i.e., placingthe standards only in the CAAregulations and relying on the title Vpermitting program) persuasive. Basedon the comments we received, and oursubsequent analysis, we narrowed ouroptions for how to permit hazardouswaste combustors subject to the newMACT standards and elaborated on ourpreferred approach in the May 1997NODA (see 62 FR 24249). In the NODA,we described an approach to place theMACT emissions standards only in theCAA regulations at 40 CFR part 63Subpart EEE, and rely onimplementation through the airprogram, including operating permitprograms developed under title V.Under this approach, which we areadopting in today’s final rule, MACT airemissions and related operatingrequirements are to be included in titleV permits; RCRA permits will continueto be required for all other aspects of thecombustion unit and the facility that aregoverned by RCRA (e.g., correctiveaction, general facility standards, othercombustor-specific concerns such asmaterials handling, risk-based emissionslimits and operating requirements, asappropriate, and other hazardous wastemanagement units).

Placement of the emissions standardssolely in part 63 appears to be the mostfeasible way to avoid duplicativepermitting requirements. We agree withthe commenters’ views that placementof the standards in both RCRA and CAAregulations would require both permitsto address air emissions. Permittingauthorities would not be able to choosewhich program would be responsible forimplementing the requirements. Placingthe standards in both sets of regulationswould obligate both programs to addressthe standards in permits issued undertheir respective authorities. Simply put,permitting authorities would not be freeto incorporate the new standards into

either CAA title V permits or RCRApermits; rather, they would need toincorporate the new standards, to somedegree, into both permits.287 Havingdetermined that placement of thestandards in both sets of regulations isnot desirable, we revisited the questionof whether one program could defer tothe other. The CAA does not provideauthority to defer to otherenvironmental statutes,288 so we couldnot place the MACT standards solely inRCRA regulations, which would haveconsequently allowed them to beincorporated only into a RCRA permit.On the other hand, RCRA does provideauthority to forego RCRA emissionsstandards in favor of MACT standardsimposed under the CAA. As statedabove in Part One, Section I, under theauthority of RCRA section 3004(a), it isappropriate to eliminate these RCRAstandards because they would only beduplicative and so are no longernecessary to protect human health andthe environment. Also as discussedthere, RCRA section 1006(b) providesfurther authority for the Administratorto eliminate the existing RCRA airemissions standards in order to avoidduplication with the new MACTstandards. Thus, we use our authority todefer RCRA controls on the airemissions to the part 63 MACTstandards, which ultimately areincorporated into title V permits issuedunder the CAA.

The majority of the commentsreceived following publication of theMay 1997 NODA supported ourpreferred approach to permitting thehazardous waste combustors. Severalcommenters expressed appreciation forthis effort, and concluded that ourapproach would avoid duplication andhave the RCRA and title V permits workto complement each other rather thanpotentially contradict each other.Although sources will still have twopermits, the scope and subject matter ofeach will be distinguishable. The title Vpermit will focus on the operation of thecombustion unit (e.g., air emissions andrelated parameters) while the RCRApermit will continue to focus on basichazardous waste management at the

facility (e.g., general facility standards,corrective action, other units, and soon). The only time there might beconditions in both RCRA and title Vpermits that address the same hazardouswaste combustor operating requirementsand limits is when there is a need toimpose more stringent risk-basedconditions, e.g., under RCRA‘‘omnibus’’ authority, in the RCRApermit. The RCRA permitting authoritywould add terms and conditions basedon the omnibus clause only if it found,at a specific facility, that the MACTstandards were not sufficient to protecthuman health or the environment. Thisissue is discussed in greater detail inPart III, Section IV (RCRA DecisionProcess). In those limited cases, sourcesand permitting agencies may agree toidentify the RCRA limit in the title Vpermit. Since one goal of the title Vprogram is to clarify a source’scompliance obligations, it will bebeneficial, and convenient, toacknowledge the existence of morestringent limits or operating conditionsderived from RCRA authority for thesource in the title V permit, even thoughthe requirements would not reflect CAArequirements. We strongly encourageRegional, State, and local permittingauthorities to take advantage of thisbeneficial option.

Some commenters continued tomaintain that flexibility to choosewhich program would permit airemissions would only be provided if wewere to promulgate the standards inboth CAA and RCRA regulations. Theyreiterated the position they had taken intheir comments on the initial proposalthat this approach would not result induplication across the programs; theydiscounted concerns over duplicativerequirements or dual enforcementscenarios by saying that it was basicallynot in a permitting authority’s bestinterests to issue duplicate permits. Wefound the contrary, that placement ofthe standards in both sets of regulationsdoes not provide flexibility for aregulatory agency to choose one permitprogram or another. Such an approachwould obligate both permits to cover airemissions and related operatingrequirements. This result does notachieve our or the commenters’objective of avoiding duplication acrossprograms. Although the actual burdenon permit writers may not be significantif, for example, the title V permit wereto just cross-reference the appropriatesections of the RCRA permit, therequirements would still be enforceableunder both vehicles, and would gothrough dual administrative processes.As mentioned above, EPA would like to



289 Title V permits are required for many moresources than those subject to the HWC MACTstandards. Currently, there are approximately20,000 sources that are subject to title V; there areonly about HWCs subject to today’s rule.

290 Within negotiated agreements, there isflexibility in Performance Partnership Grants tostrategically move funds, and flexibility inPerformance Partnership Agreements found in theNational Environmental Performance PartnershipSystem to strategically integrate programs.

291 If the HWC MACT standards are the onlyapplicable CAA requirements, however, then therewould be no other components of a title V permitfor the source.

292 Some States have successfully issued ‘‘one-stop’’ multimedia permits which include provisionsfrom both the CAA and RCRA programs in a singlepermit. However, it is EPA’s understanding thatthese permits cite both the RCRA and CAAauthority; thus, the potential for enforcement underboth statutes still remains.

avoid this type of dual enforcement anddual process scenario in implementingthe new standards.

3. What Considerations Were Made forEase of Implementation?

Our approach in the final rule doesnot limit the options available to statepermitting authorities for implementingthe new standards. The primary concernabout which program (RCRA or CAA)assumes lead responsibility foradministering air emissionsrequirements appears to revolve aroundresource issues. The RCRA program hasbeen the lead program for permittinghazardous waste combustors for manyyears, consequently, RCRA programstaff have developed a great deal ofexpertise in this area. They are familiarwith source owners and operators, thecombustion units, and specialconsiderations associated withpermitting hazardous waste combustionactivities. Some commenters areconcerned that by deferring regulationof air emissions standards to the CAA,that expertise will no longer beavailable. They express doubt about theability of air toxics implementationprograms and title V programs to takeon these sources, given the complexityof hazardous waste combustoroperations and the volume of title Vpermits that need to be issued over thenext several years.289

In response to these comments, wenote that many State Air programscurrently play key roles in permittinghazardous waste combustors underRCRA. Furthermore, States may findthat much of the expertise used toregulate other air sources is directlyapplicable to regulating the hazardouswaste combustor sources subject to thenew MACT standards, and that theresources in their air programs aresufficient to handle these additionalsources. If, however, a State sharescommenters’ concerns that its airprogram, as it currently exists, may notbe able to take on these sources, theState may continue using the resourcesand expertise of its RCRA program eventhough the new standards are beingpromulgated as part of the CAAregulations.

In the May 1997 NODA, we discussedthe flexibility afforded to States bycodifying the standards under only onestatute (see 62 FR 24246). Two potentialoptions were described in the NODA forhow this might be achieved: (1) A Statecould simply have its RCRA staff

implement the hazardous wastecombustor MACT standards; or (2) aState could formally incorporate thestandards into its State RCRA program.In response to the NODA, some Stateenvironmental agencies commentedthat, as a matter of State law, theywould not be able to incorporate thenew standards into their authorizedhazardous waste programs unless theyare included in federal RCRAregulations. We acknowledge, therefore,that some States may not be able topursue the second option. In any case,we recommend against this optionbecause, as discussed below, it wouldperpetuate having duplication betweentwo permits. The first option would,however, still be feasible. For example,the States could explore the flexibilityprovided through PerformancePartnership Agreements 290 if theywould like to have their RCRA programstaff continue their work with thehazardous waste combustors.

If a State chooses to use either of theabove options to continue applyingRCRA expertise to hazardous wastecombustors, we anticipate that RCRAprogram staff would be responsible formany of the implementation activities,such as reviewing documents submittedby the source (e.g., the Notice of Intentto Comply, the progress report, and theperformance test plan), and workingwith the source to resolve anydifferences (e.g., on anticipatedoperating requirements or on results ofcomprehensive performance tests).

Where the process issues would startto diverge between the two options is atthe actual permitting stage. Under thefirst option (RCRA staff implementingCAA regulations), the standards wouldbe incorporated only into title Vpermits. Title V permits cover a widerange of applicable requirements underthe CAA; the hazardous wastecombustor MACT standards are likely tobe just one piece.291 We believe that theRCRA permit writer would draft thehazardous waste combustor portion ofthe title V permit, and would coordinatewith the title V permit writer in theCAA program who has responsibility forthe source’s overall permit to ensurethat the hazardous waste combustorportion is properly incorporated. Inshort, the RCRA permit writer would

simply be developing a component of atitle V permit instead of developing acomponent of a RCRA permit. Statepermitting authorities that wish tocontinue using their RCRA expertisewill undoubtedly explore this approach.

If a State pursues the second optionof incorporating the new hazardouswaste combustor MACT standards intoits State RCRA program, there may stillbe a need to incorporate the standardsinto both title V and RCRA permits. TheCAA does not provide authority to defertitle V permitting to otherenvironmental programs. Thus, thesource would still be subject to title Vrequirements (i.e., a RCRA permit couldnot ‘‘replace’’ a title V permit).Furthermore, an EPA Region or a Statewho chooses to obtain authorization forthe hazardous waste combustor MACTstandards under RCRA would also haveto start implementing the new standardsunder CAA authority (including title Vpermitting requirements) even as theState begins efforts to incorporate thestandards into its State RCRA program.

Although close cooperation betweenthe RCRA and title V permit writerscould minimize duplicative efforts indeveloping permits and avoidconflicting conditions in the twopermits (for example, by putting theconditions in one permit and justreferencing them in the other), thisapproach still results in the potential forenforcement and citizen suits underboth permits. 292 As discussed above, weintend to avoid duplicate permittingand enforcement scenarios forhazardous waste combustor MACTstandards; thus, we strongly encourageStates that choose to pursue thisapproach to develop implementationschemes that minimize the potential forsuch duplication to the extentpracticable.

B. What Is the Applicability of the TitleV and RCRA Permitting Requirements?

This section briefly summarizes theapplicability of both title V and RCRApermitting requirements under thepermitting scheme discussed in SectionXI. A. above. It also discusses therelationship of this permitting schemeto both the proposed revisions tocombustion permitting procedures fromJune 1994 and to the RCRApreapplication meeting requirements.Our decision to subject hazardous wastecombustors that are considered area


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