9176 federal register vol. 53, no. 54 monday, march 21 ... · technical development document may be...

Federal Register / Vol. 53, No. 54 / Monday, March 21, 1988 / Rules and Regulations

ENVIRONMENTAL PROTECTIONENVIRONMENTAL PROTECTIONAGENCY

40 CFR Part 425

[FRL 3304-6]

Leather Tanning and FinishingIndustry Point Source CategoryEffluent Limitations Guidelines,Pretreatment Standards, and NewSource Performance Standards

AGENCY: Environmental ProtectionAgency (EPA).ACTION: Final rule.

SUMMARY: This final rule establisheseffluent limitations guidelines andstandards limiting the discharge ofpollutants into navigable waters of theUnited States and the introduction ofpollutants into publicly owned treatmentworks (POTW) by-existing and newsources engaged in leather tanning andfinishing. EPA is promulgating theseamendments in accordance with asettlement agreement with the Tanners'Council of America, Inc. (The Tanners'Council of America, Inc., wasredesignated the Leather Industries ofAmerica, Inc., in 1985). The agreementsettles a dispute between the Counciland EPA that was the subject of apetition for judicial review of the finalleather tanning and finishing rulepromulgated by EPA on November 23,1982 (47 FR 52848).

This final rule, which was proposedon January 21, 1987 (52 FR 2370), (1)adds a new analytical method for thedetermination of the presence of sulfidein wastewaters for use in the Hair Saveor Pulp, Non-Chrome Tan, Retan-WetFinish Subcategory (Subpart C); (2)clarifies procedural requirements forpublicly owned treatment works tofollow in determining whether sulfidepretreatment standards are applicable;(3) revises certain of the effluentlimitations for "best practicable controltechnology currently available" (BPT)and new source performance standards(NSPS); (4) changes the pH pretreatmentstandard for tanneries falling under theprovisions of Subpart C; and (5) clarifiesthe production levels below which thechromium pretreatment standards forexisting sources (PSES) do not apply. Inaddition, EPA clarifies in the preambleto this final rule its statements onmedian water use -ratios, changes insubcategorization, tanneries with mixedsubcategory operations, and compositesamples of effluent discharges frommultiple outfalls.DATES: In accordance with 40 CFR 23.2and 40 CFR 23.11, this rule shall beconsidered issued for the purposes of

judicial review at 1:00 p.m. easterndaylight time on April 4, 1988. This ruleshall become effective May 4, 1988.

Under section 509(b)(1) of the CleanWater Act as amended by section505(a)(2) of the Water Quality Act of1987, judicial review of this rule may bemade by filing a petition for judicialreview in the United States Court ofAppeals not later than 120 days after therule is considered issued for purposes ofjudicial review. Under section 509(b)(2)of the Clean Water Act, therequirements in this rule may not bechallenged later in civil or criminalproceedings brought by EPA to enforcethese requirements.ADDRESSES: Address questions on thefinal rule to Rexford R. Gile, Jr.,Industrial Technology Division (WH-552), U.S. Environmental ProtectionAgency, 401 M Street SW., Washington,DC 20460, Attention: Leather Tanningand Finishing Industry Final Rule. Thebasis for this rule is detailed in the"Supplemental Development Documentfor Effluent Limitations Guidelines forthe Leather Tanning and Finishing PointSource Category." A copy of thistechnical development document maybe obtained from the National TechnicalInformation Service, Springfield,Virginia 22161, (703) 487-6000. Technicalinformation may be obtained by writingto Rexford R. Gile, Jr., IndustrialTechnology Division (WI-552), U.S.Environmental Protection Agency, 401 MStreet SW., Washington, DC 20460 or bycalling (202) 382-7146.

The record for the final rule will beavailable for public review not laterthan April 4, 1988, at the EPA PublicInformation Reference Unit, RoomM2904 (Rear) (EPA Library). The EPApublic information regulation (40 CFRPart 2) provides that a reasonable feemay be charged for copying.FOR FURTHER INFORMATION CONTACT:Rexford R. Gile, Jr., (202) 382-7146.SUPPLEMENTARY INFORMATION:

Organization of this Notice

I. Legal Authority.II. Background.A. Prior Regulations.B. Challenge to the 1982 Regulation by the

Tanners' Council of America, Inc.C. Settlement Agreement.III. Amendments to the Leather Tanning

and Finishing Point Source CategoryRegulation.

A. Alternative Sulfide Analytical Method.1. TCA Concerns and EPA Response.2. Amendment to § 425.02 General

Definitions.3. Amendment to § 425.03 Sulfide

Analytical Methods.B. Applicability of Sulfide Pretreatment

Standard.1. TCA Concern and EPA Response.

2. Amendment to § 425.04 Applicability ofSulfide Pretreatment Standard.

C. Changes to Effluent LimitationsGuidelines and Standards Based on RevisedWater Use Ratios, pH Pretreatment Standard,and Changes to the Small TanneryExemption.

1. Changes to Effluent LimitationsGuidelines and Standards.

2. PSES for pH.3. Small Tannery Exemption.IV. Clarifications.A. Changes in Subcategorization.B. Tanneries with Mixed Subcategory

Operations.C. Multiple Qutfalls.V. Environmental Impact of Amendments.VI. Economic Impact of Amendments.VII. Public Participation and Response to

Comments.VIII. Executive Order 12291.IX. Regulatory Flexibility Analysis.X. OMB Review.XI. List of Subjects in 40 CFR Part 425.

I. Legal Authority

These amendments to 40 CFR Part 425are being promulgated under theauthority of sections 301, 304(b), (c), (e),and (g), 306(b) and (c), 307(b) and (c),308 and 501 of the Clean Water Act [theFederal Water Pollution Control ActAmendments of 1972 as amended by theClean Water Act of 1977 and the WaterQuality Act of 1987 (the "Act")]; 33U.S.C. 1311, 1314(b), (c), (e), and (g),1316(b) and (c), 1317(b) and (c), 1318,and 1361; 86 Stat. 816, et seq., Pub. L. 92-500; 91 Stat. 1567, Pub. L. 95-217; andPub. L. 100-4. These amendments to theregulation are also being promulgated inresponse to the Settlement Agreement inTanners' Council of America, Inc. v.US. Environmental Protection Agency,No., 83-1191, (4th Cir.).

II. Background

A. Prior Regulations

EPA promulgated a regulation onApril 9, 1974, establishing effluentlimitations guidelines and standards forthe leather tanning and finishing pointsource category based on the bestpracticable control technology currentlyavailable ("BPT"), the best availabletechnology economically achievable("BAT"), new source performancestandards ("NSPS") for new directdischargers, and pretreatment standardsfor new indirect discharges ("PSNS") (39FR 12958; 40 CFR Part 425, Subparts A-F). The Tanners' Council of America,Inc., (TCA), challenged this regulation,and the U.S. Court of Appeals for theFourth Circuit left BAT and PSNSundisturbed, but remanded the BPT andNSPS limitations and standards forseveral reasons (see Tanners' Council ofAmerica, Inc. v. Train, 540 F.2d 1188 (4thCir. 1976)).

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On March 23, 1977 (42 FR 15696), EPApromulgated pretreatment standards.forexisting sources ("PSES") for the leathertanning and finishing industry. Thisregulation established specific pHstandards and other pretreatmentstandards for existing indirectdischargers to avoid interference withPOTWs. This rule was not challenged.

EPA proposed a new regulation (44 FR38746, July 2, 1979) establishing effluentlimitations guidelines and standards forthe leather tanning and finishing pointsource category based on revised BPTand NSPS to replace the remanded BPTand NSPS limitations and standards,new best conventional pollutant controltechnology ("BCT") limitations, andrevised BAT, PSES, and PSNSlimitations and standards. EPA acceptedcomments on the proposed regulationuntil April 10, 1980. The leather tanningand finishing industry commented thatthe data and supporting record materialrelied upon by EPA in proposing theregulation contained a large number oferrors. The Agency responded bycompletely reviewing the entire database and all documentation supportingthe rulemaking, and by acquiringsupplemental data during and after thecomment period.

On June 2, 1982 (47 FR 23958), EPAmade available for public review andcomment supplementary technical andeconomic data and relateddocumentation received after proposalof the regulation. The Agency alsosummarized the preliminary findings onhow the supplementary record materialsmight influence the final rulemaking.

The final regulation for the leathertanning and finishing industry pointsource category was promulgated onNovember 23,'1982 (47 FR 52848) andestablished effluent limitationsguidelines and standards to controlspecific toxic, nonconventional, andconventional pollutants for ninesubcategories in the Leather Tanningand Finishing Category.Subpart A-Hair Pulp, Chrome Tan,

Retan-Wet Finish Subcategory(Subcategory 1)

Subpart B-Hair Save, Chrome Tan,Retan-Wet Finish Subcategory(Subcategory 2)

Subpart C-Hair Save or Pulp, Non-Chrome Tan, Retan-Wet FinishSubcategory (Subcategory 3)

Subpart D-Retan-Wet, Finish-SidesSubcategory (Subcategory 4)

Subpart E-No Beamhouse Subcategory(Subcategory 5)

Subpart F-Through-the-BlueSubcategory (Subcategory 6)

Subpart C-Shearling Subcategory(Subcategory 7)

Subpart H-Pigskin Subcategory(Subcategory 8)

Subpart I-Retan-Wet Finish-SplitsSubcategory (Subcategory 9)BPT effluent limitations guidelines

were established'for all subcategoriesbased on high solids extended aerationactivated sludge biological treatment.They included production-based effluentlimitations (kg/kkg or lb/1,000 lb or rawmaterial) for one toxic pollutant (totalchromium), three conventionalpollutants (BOD5, TSS, oil and grease),and established an acceptable pH range.BPT production-based effluentlimitations were derived usingsubcategory median water use ratios,attainable effluent concentrations, andvariability factors.

BAT and BCT effluent limitationsguidelines were also established for allnine subcategories in the leather tanningand finishing point source category. Thetechnology basis and production-basedeffluent limitations guidelines for BATand BCT were the same as those for thepromulgated BPT effluent limitationsguidelines. The BCT effluent limitationsguidelines control three conventionalpollutants (BOD5, TSS, oil and grease),and established an acceptable pH range.The BAT effluent limitations guidelinescontrolled one toxic pollutant (totalchromium).

The production-based NSPS for allnine subcategories limited one toxicpollutant (total chromium) and threeconventional pollutants (BOD5, TSS, oiland grease), and established anacceptable pH range. NSPS were basedon the same technology, effluentconcentrations, and variability factorsas BAT, but the production-basedlimitations for NSPS were different fromthose for BAT because the NSPSlimitations were based on reducedwater use ratios.

The final regulation establishedconcentration-based categoricalpretreatment standards for existing andnew source indirect dischargers for onetoxic pollutant (total chromium) for allnine subcategories except for existingsmall indirect dischargers insubcategories in Subparts A, C, and I.

Concentration-based categoricalpretreatment standards were alsoestablished for the control of sulfides insubcategories in Subparts A, B, C, F, andH where unhairing operations areincluded. However, the regulationincluded a provision which allows aPOTW to certify to the Regional WaterManagement Division Director of EPA inthe appropriate Regional Office, inaccordance with § 425.04, that thedischarge of sulfide from a particularfacility does not interfere with its

treatment works. If this certification ismade, and EPA determines that thesubmission is adequate, EPA willpublish a notice in the Federal Registeridentifying the facility where the sulfidepretreatment standard would not apply.

The cost of pretreatment technologycan be minimized by reducing to themaximum extent feasible the volume ofwastewater treated. Therefore, theAgency used reduced water use ratios tocalculate the costs of PSES/PSNStechnology for indirect dischargersinstead of median water use ratios forexisting sources.

B. Challenge to the 1982 Regulation bythe Tanners' Council of America, Inc.

The Tanners' Council of America, Inc.(TCA), filed a petition for judicialreview of several aspects of the finalregulation in the U.S. Circuit Court ofAppeals for the Fourth Circuit on March2, 1983 (Tanners' Council of America,Inc. v. U.S. Environmental ProtectionAgency, No. 83-1191), and followed thisby filing with EPA an administrativePetition for Reconsideration on May 9,1983. The Agency responded bycompletely reviewing the entire database and all documentation supportingthe rulemaking, and by acquiringsupplemental data. After extensivediscussions, TCA and EPA resolved theissues raised by the Council through asettlement agreement.

C. Settlement Agreement

On December 11, 1984, TCA and EPAentered into a comprehensive settlementagreement which resolved all issuesraised by TCA in its petitions. EPAagreed to propose regulatoryamendments and preamble language tothe leather tanniig and finishingregulation and to solicit comments onthe regulatory and preamble language.TCA agreed to move to dismiss itspetition for judicial review andvoluntarily withdraw the "Petition forReconsideration" if each provision ofthe final leather tanning and finishingindustry regulation and each preamblestatement is substantially the same asthat called for by the settlementagreement.

Copies of the settlement agreementwere sent to EPA Regional Offices andState NPDES permit-issuing authoritieson December 21, 1984. In accordancewith the settlement agreement, EPAproposed regulatory amendments andpreamble language to the leathertanning and finishing regulation onJanuary 21, 1987 (52 FR 2370) andsolicited comments regarding theseproposed amendments. The comment

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period on the proposal closed onFebruary 20, 1987.

As part of the settlement agreement,TCA and EPA jointly requested the U.S.Court of Appeals for the Fourth Circuitin Tanners' Council of America, Inc. v.EPA to stay the effectiveness of thesections of 40 CFR Part 425 which EPAhad agreed to propose to amend,pending final action by EPA on eachproposed amendment. On February 22,1985, the Court entered an Order stayingthe following sections of the regulationpromulgated on November 23, 1982:§ 425.02(a); § 425.03; § 425.11, except forthe pH limitations; § 425.15(b); § 425.31,except for the pH limitation; the pHlimitation in § 425.35(a); § 425.35(b);§ 425.41, except for the p1- limitation;§ .425.44, except for the pH limitation;§ 425.51, except for the p1-I limitation;§ 425.61, except for the pH limitation;§ 425.64, except for the pH limitation;§ 425.71, except for the pH limitation;§ 425.91, except for the pH limitation;and § 425.95(b). EPA is amending thesesections in this final rule in accord withthe settlement agreement.

All effluent limitations guidelines andstandards contained in the final leathertanning and finishing industry regulationpromulgated on November 23, 1982,which are not specifically listed in theseamendments to the regulation, were notstayed by the Order entered by theCourt. In addition, EPA is not deleting ormodifying any of the effluent limitationsguidelines and standards not affected bythe settlement agreement or Order.

Ill. Amendments to the Leather Tanningand Finishing Point Source CategoryRegulation

In the final rule, EPA is amending Part425 in accordance with the settlementagreement to (1) allow use of a newalternative sulfide analytical method, (2)clarify the procedures to be followed bya POTW when changed circumstancesjustify application of sulfidepretreatment standards wherepreviously waived, or a certification bya POTW that the discharge of sulfidewill not interfere with the operation ofthe POTW, (3) revise BPT effluentlimitations guidelines and NSPSstandards based on corrected and morecomplete information, and (4) allow thesmall tannery exemption withoutrestriction as to the number of workingdays per week. These amendments arediscussed in this section.

A. Alternative Sulfide AnalyticalMethod

1. TCA Concerns and EPA Response.EPA had promulgated a categoricalsulfide pretreatment standard andrequired all facilities to use the Society

of Leather Trades' Chemists' "Methodfor Sulfide Analysis SLM 4/2" in whichthe sulfide solution is titrated withstandard potassium ferricyanidesolution in the presence of a ferrousdimethylglyoxime ammonia complex(§ 425.03). TCA and some industrymembers conducted testing to determinethe validity of this analytical method.These test results revealed the followingproblems with the SLM 4/2 method.

a. The method described in thepreviously promulgated § 425.03(c)(1)provides for the removal of thesuspended matter by rapid filtrationthrough either glass wool or coarse filterpaper. The lack of standardization ofglass wool could potentially causeinconsistent analytical results.

b. The titrant equivalence statementas set forth in the previouslypromulgated § 425.03(c)(4) will lead toconfusion in the reporting of analyticalresults because it expresses the resultsin terms of sodium sulfide instead ofsulfide upon which the pretreatmentstandards are based.

c. Colored tannery wastewater,especially vegetable tanners'wastewater, makes it difficult to detectthe destruction of the pink color at theend point. Additionally, certain simplephenolic substances (pyrogallol andpyrocatechol), which are modelsubstances for the nontannins ofvegetable tanning materials, consumethe ferricyanide titrant under theprescribed SLM 4/2 conditions. Theseinterfering substances may yield falseresults.

In response to the first problem, EPAis amending the promulgated approvedmethod to delete glass wool as analternative rapid filtration medium. EPAis also amending the previouslypromulgated method to specify use of acoarse filter paper. In response to thesecond problem, EPA is amending themethod to express the results of thetitrant equivalence statement in terms ofmg. per liter of sulfide which is the basisfor the pretreatment standards.

In response to the third problem, EPAand TCA conducted a cooperativesampling and analytical methodsdevelopment program for vegetabletanning wastewaters using both thepromulgated SLM 4/2 method and amethod suggested by TCA, the modifiedMonier-Williams method. Raw andpretreated wastewaters were collectedat seven tanneries, including twovegetable tanning tanneries, for analysisby EPA and TCA. The analytical datashowed that the modified Monier-Williams method was able to measuresulfide in vegetable tannery wastewaterwhen wastewater color preventeddetection of the end point color change

using the SLM 4/2 procedure. The dataalso showed that the method producedconsiderably better spike recoveriesthan the SLM 4/2 procedure. These dataand EPA's summary of the results arepart of the record of this rulemaking.The modified Monier-Williams method,thus, is an acceptable procedure forpretreatment standard compliancemonitoring in the leather tanning andfinishing industry. EPA is amending Part425 by including the modified Monier-Williams method as a sulfide analyticalprocedure for facilities with vegetabletanning wastewaters and as analternative sulfide analytical procedurefor other tanneries.

2. Amendment to §425.02 GeneralDefinitions. EPA is making two minorchanges to the general definitionssections to address analytical methodsissues. EPA is defining "sulfide" in§ 425.02(a) as total sulfide as measuredby either the potassium ferricyanidetitration procedure ("Method for SulfideAnalysis SLM 4/2") in Appendix A toPart 425 or the modified Monier-Williams procedure described inAppendix B to Part 425. This is atechnical change required to allow useof the new procedures. These twoanalytical procedures are moved toappendixes to the final rule for theconvenience of the user.

Under the settlement agreement, EPAagreed to propose that the MinimumReportable Concentration (MRC] shouldbe determined periodically in each ofthe two sulfide analytical procedures byeach participating laboratory inaccordance with the proceduresspecified in "Methods for ChemicalAnalysis of Municipal and IndustrialWastewater," EPA-600/4-82-057, July1982, EMSL, Cincinnati, OH 45268. Theterm MRC is not explicitly defined in thesettlement agreement or in the 1982"Methods" document cited. Rather, the1982 "Methods" document describes theMethod Detection Limit (MDL)procedure which is also described inAppendix B to 40 CFR Part 136. EPAinterprets MRC to be synonymous withthe MDL procedure described inAppendix A to the 1982 "Methods"document and Appendix B to 40 CFRPart 136. Therefore, the MDL procedureis used as the MRC method. For theconvenience of the user, the definitionand procedure for the determination ofthe Method Detection Limit is containedin Appendix C to Part 425.

3. Amendment to §425.03 SulfideAnalytical Methods. The previouslypromulgated § 425.03 describes thepotassium ferricyanide titration (SLM 4/2) method in detail. As explained above,this method and the modified Monier-

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Williams method are described in newappendixes to Part 425. Section 425.03 isamended to provide that the potassiumferricyanide method is approved foranalysis of sulfide except for thosetanneries covered by Subpart C (HairSave or Pulp, Non-Chrome Tan, Retan-Wet Finish Subcategory). For thesetanneries, the modified Monier-Williamsmethod is the approved method;tanneries in other subcategories mayalso use the modified Monier-Williamsmethod to detect sulfide.

3. Applicability of Sulfide PretreatmentStandard

1. TCA Concern and EPA Response.The previously promulgated § 425.04provided that, until October 13, 1983,POTWs may take steps to certify thatsulfide pretreatment standards do notapply. (40 CFR 425.04(c)). The previousrule did not provide a procedure bywhich POTWs could revoke apreviously issued certification ofinapplicability. TCA criticized theprovision of § 425.04 under which, afterOctober 13, 1983, a POTW is precludedfrom certifying that the sulfidepretreatment standards should not applyto a particular facility. TCA noted thatthere may be changed circumstancesafter that deadline under which it maystill be appropriate for a POTW to allowsuch a certification. EPA agrees thatthere may be changed circumstancesafter the October 13, 1983 deadlinewhich would justify both the issuanceand revocation of a certification as tothe applicability or inapplicability of thesulfide pretreatment standards, and isamending § 425.04 to permit a POTW toinitiate proceedings, revoke, or issuecertification on the inapplicability of thesulfide pretreatment standardssubsequent to the October 13, 1983deadline.

2. Amendment to §425.04Applicability of Sulfide PretreatmentStandard. EPA is amending § 425.04 byadding paragraphs (d)(1), (d)(2), and (e)to § 425.04. The amended § § 425.04(d) (1)and (2) provide a procedure for POTWsto revoke a previously issuedcertification of inapplicability of thesulfide pretreatment standard. If, as aresult of this revocation, the sulfidepretreatment standards are to beapplicable to an indirect discharger, thedischarger will be required to complywith these standards no later than 18months from the publication date of theFederal Register notice announcing therevocation.

EPA is amending § 425.04(e) whichauthorizes POTWs to initiateproceedings to certify that sulfide

pretreatment standards should not applyto specified facilities after October 13,1983. Under this subsection, a POTWmay determine that circumstances havearisen since that date that justify adetermination that the sulfidepretreatment requirements should notapply. The POTW may propose tocertify that the pretreatment standarddoes not apply and may initiateproceedings to this end. Thiscertification would be governed by theexisting certification procedures andtime intervals in § § 425.04 (b) and (c).

C. Changes to Effluent LimitationsGuidelines and Standards Based onRevised Water Use Ratios, pHPretreatment Standard, and Changes tothe Small Tannery Exemption

1. Changes to Effluent LimitationsGuidelines and Standards. TCAcriticized EPA's median flow ratios forthree subcategories (Subparts D, F, andI) alleging that the flow ratios developedby EPA were erroneous based on newwater use data submitted by TCA. EPAhad developed median flow ratios foreach subcategory to derive production-based effluent limitations for directdischarging facilities.

After reviewing the revised data basefor the subcategory median and newsource water use ratios, EPA determinedthat changes should be made in themedian water use ratios for a number ofsubcategories. Table 1 reflects therevisions in median water use ratios forexisting plants as well as revisions inthe number of plants in the subcategorydata bases and the number of plantsachieving median water use ratios.Table 2 reflects the revisions in the newsource water use ratios and in thenumber of plants achieving these wateruse ratios.

TABLE 1

Plants in data base

Median Number of Number ofSubcate- water use plants in plants in

gory ratio (gals/ subcate- data basesb) ata achievinggory data water use

base ratios

1 6.6 34 172 5.8 4 33 4.8 11 64 6.3 7 45 5.7 10 56 2.3 3 27 10.7 2 18 5.0 2 19 4.1 6 3

TABLE 2

N Number ofNew source Plants in dataSubcategory water use ratio Pas in(gals/Ib) base achieving

water use ratio

1 4.3 62 4.9 13 4.2 44 4.6 25 3.8 36 2.1 17 9.4 18 4.1 19 2.5 2

As a result of the review of EPA'sdata base, supplemented by informationsupplied by TCA, and corrections toidentified errors in the interpretation ofexisting water use data, the subcategorymedian and new source water use ratiosused to establish BPT and NSPSlimitations and standards wererecalculated. These amendments willresult in BPT effluent limitationsguidelines for Subparts A, D, F, G, and Ithat are less stringent than those in thefinal regulation (47 FR 52848, November23, 1982), while the BPT limitations forSubparts C and E will be more stringentthan those in the final regulation. NSPSfor subparts D and F will be lessstringen t than those in the finalregulation. The SupplementalDevelopment Document for EffluentLimitations Guidelines and Standardsfor the Leather Tanning and FinishingIndustry Point Source Category".documents the basis for the changes toeffluent limitations guidelines andstandards based on revised water useratios.

2. PSESforpH. EPA established a pHrange of 7.0 to 10.0 for leather tannerieswith alkaline wastestreams in the 1982final regulation. EPA established 10 asthe uppermost level of the pH rangebecause of the solubility of chromium atpH levels in excess of 10. TCA arguedthat EPA should establish a waiverprocedure to allow relief for tannerieswith a pH in excess of 10 in certaincircumstances.

After careful consideration, EPAconcluded that a waiver from the higherstandard would be unduly complicated.In response to TCA's request, EPA didagree todelete the higher (alkaline) pHstandard for vegetable tanneries inSubpart C only (§ 425.35(a)). EPA is lessconcerned about the chromiumsolubility for vegetable tanneries sincethese tanneries typically discharge lowlevels of chromium. The higher pHpretreatment standards for the other

.subcategories will remain as

9180 Federal Register *1 Vol. 53, No. 54 I Monday, March 21, 1988 / Rules and Regulationspromulgated because they will reducethe probability of chromium solubility.The low (acid) pH standard has beenretained to ensure that the formation ofhydrogen sulfide gas is minimized.

3. Small Tannery Exemption. Thepretreatment standards for the leathertanning and finishing industry providethat chromium standards are nowinapplicable to small plants in SubpartsA, C, or I which discharge to publiclyowned treatment works if these plantsproduce less than a specified number ofhides/splits per day .and a -specifiedweight of hides/splits per year in theirrespective subcategories. In a correctionnotice dated June 30, 1983, the Agencyspecified the -annual weight basis aswell as the number of working days peryear underlying the specified hide andsplit limits (48 FR 30115). Subsequent todiscussing this matter with TCA, theAgency has reconsidered this issue. TheAgency is deleting all references to theannual weight basis and the number ofworking days per year underlying thespecified hide and split limits.Accordingly, tanneries with a seven-dayworkweek could qualify for theexemption.

Therefore, EPA is amending SubpartA (§ 425.15(b)), Subpart C § 425.35-)),and Subpart I (§ 425.95(b)) by deletingreferences to the annual weight basisand the number of working days peryear that were specified in thecorrection notice (48 FR 30115, June 30,1983) to" the final regulation for the smalltannery exemption from pretreatmentstandards for chromium. The Agencyhas not, however, made any changes tothe underlying exemption based -onnumbers of hides or splits per day.

IV. Clarifications

In addition to the amendmentsdiscussed in Section III, EPA isclarifying several issues: Changes insubcategorization, .classification oftanneries with mixed subcategory

operations, and multiple outfalls. Theseissues are addressed below.A. Changes in Subcategorization

Under 40 CFR 403.6(a) of the generalpretreatment regulations, an existingindustrial user or a POTW may seekWritten certification from the ApprovalAuthority as to whether the industrialuser falls within a particularsubcategory of a promulgatedcategorical pretreatment standard.Existing users must make the requestwithin 60 days after the effective date ofa pretreatment standard for asubcategory under which the user maybe included or within 60 days after theFederal Register notice announcing theavailability of the technical documentfor the subcategory. New sources mustrequest this certification prior tocommencing discharge.

Persons have inquired as to theprocedures that existing leather tanningfacilities should use to seek an Agencydetermination if the facility decides tochange its subcategorization subsequentto the expiration of the 60-day deadlineunder.40 CFR 403.6(a). In fact, 40 CFR403.6(a),does not preclude leathertanning and finishing facilities fromchanging operations which would inturn automatically change theirsubcategorization status. Facilities thatare planning to change theirsubcategorization status and are unsurewhichsubcategory they will fall intoshould request written certification fromthe Approval Authority as to whetherthe facility falls within a particularsubcategory prior to commencingdischarges which would fall within thatsubcategory.

B. Tanneries With Mixed SubcategoryOperations

The pretreatment standards forchromium are -not applicable to plantswith mixed subcategory operations ifthe greatest part of the plant'sproduction is in either subcategory 1, 3,-or 9 and if the total plant production isless than the specified number of hides

or splits per day for the particularsubcatqgory. The intent of thisexemption is to exclude small plantsfrom thechromium pretreatmentstandards, not to-exclude processingoperations at medium or large plants.

C. Multiple Outfalls

Most indirect discharging plantscombine theirprocess wastewaters anddischarge them all through one outfall.The Agency has costed this approach byincluding costs for internal plant pipingfor wastewater collectionas well ascontingency costs to account for anyunforeseen site specific costs.

If, however, an indirect dischargingplant does not choose to combine itsprocess wastewaters for treatment andto discharge them through one outfall, acomposite sampling of the multipleoutfalls could be acceptable. A singlecomposite sample for multiple outfallsmust be comprised of representativeprocess wastewaters from each outfall.A composite sample must be combinedin proportions determined 'by the ratio ofprocess wastewater flow in each outfallto the total flow of process wastewatersdischarged through all outfalls. Ifnonprocess wastewater is combinedwith process wastewater or if a planthas operations in more than onesubcategory, the plant would have touse -the "combined wastestreamformula" in 40 CFR 403.6(e) to make thiscalculation. Flow measurements foreach outfall must be representative of,the plant's operation. An analysis of thetotal sample would then be compared tothe applicable categorical standard todetermine compliance.

V. Environmental Impact ofAmendments

EPA estimates that the industry-widedirect BPT discharge of conventional-and toxic pollutants under the finalleather tanning and finishing regulationas amended by these amendments willincrease less than four percent byweight as reflected-in Table.3.

TABLE 3.-COMPARISON OF INDUSTRY-WIDE DIRECT-BPT DISCHARGES OF CONVENTIONAL AND Toxic POLLUTANTS UNDER FINAL ANDAMENDED REGULATIONS FOR LEATHER TANNING AND FINISHING

Discharge (Ibs/yr) PercentPollutant Final Amended Increase increase

regulation regulation

S O D ....... ...... .. .................. ... ;.... ............. ............... . :.. .................................... ................ ;.. ........................ :....... ...... ... 9 13 ,0 0 0 9 4 9 ,0 0 0 36 ,0 00 3 .9SS ............................................................................. . .............................................................. ............. 1,330,000 1 3 0:000 50,000 3.8

O il & grease .................................................................................................................................. ............... 381,000 392,000 11,000 '2:9Total chrom ium ................. ................................................................................................................................................ 19 300 19 900 600 3.1

IFir al regulation, 47 FR 52848, November 23, 1982.

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VI. Economic Impact of Amendments

These amendments will not alter therecommended technologies forcomplying with the leather tanning andfinishing regulation. The Agencyconsidered the economic impact of theregulation when the regulation waspreviously promulgated (see 47 FR528481. These amendments will not alterthe determinations with respect to theeconomic impact to leather tanning andfinishing facilities.

VII. Public Participation and Responseto Comments

This regulation was proposed onJanuary 21, 1987 (52 FR 2370). Thecomment period ended on February 20,1987. Only one commenter, the LeatherIndustries of America, Inc. ("LIA"),formerly Tanners' Council of America,Inc., the principal trade association ofthe United States leather industry,submitted comments pointing out a fewtypographical errors in the proposedregulation to modify the effluentlimitations guidelines and pretreatmentstandards for the leather tanning andfinishing point source category. EPAhas, in today's final rule, corrected theseminor typographical errors. In theircomments, LIA stated that, subject tothese minor comments, the proposedrulemaking, if finally adopted, wouldsubstantially comply with therequirements of the settlementagreement. Moreover, in general, LIAvoiced full support for the Agency'samended regulatory and preamblelanguage as set forth in the proposal.

VIII. Executive Order 12291

Executive Order 12291 requires EPAand other agencies to perform regulatoryimpact analyses on major regulations.Major rules are defined as those whichresult in an annual cost of $100 millionor more, or meet other economic impactcriteria, such as cause major increasesin costs and/or prices, or significantadverse effects on the ability ofdomestic producers to compete withforeign enterprises, or on competition,investment, productivity, or innovations.The 1982 final regulation for the leathertanning and finishing industry was not amajor rule according to thesedefinitions, and, therefore, did notrequire a formal regulatory impactanalysis. This rulemaking also satisfiesthe requirements of the Executive Orderfor a non-major rule.

IX. Regulatory Flexibility Analysis

Under the RegulatoryFlexibility Act, 5U.S.C. 601 et seq., EPA must prepare aRegulatory Flexibility Analysis for allregulations that have a significant

impact on a substantial number of smallentities. In the preamble to the 1982 finalrule, EPA concluded that significantimpacts on small entities had beeneliminated by exempting small tannersfrom chromium PSES. That conclusion isequally applicable to these amendments.The Agency is not, therefore, preparinga formal analysis for these amendments.

X. OMB Review

This final rule was submitted to theOffice of Management and Budget forreview as required by Executive Order12291. Any comments from OMB to EPAand any EPA response to thosecomments are available for publicinspection at Room 2904, U.S.Environmental Protection Agency, 401 MStreet SW., Washington, DC from 9:00a.m. to 4:00 p.m. Monday through Friday,excluding Federal holidays.

List of Subjects in 40 CFR Part 425

Leather, Leather Tanning andFinishing, Water Pollution Control,Wastewater Treatment and Disposal.

Dated: March 2, 1988.Lee M. Thomas,Administrator.

For the reasons set out in thepreamble, EPA is amending Part 425,Subchapter N, Chapter 1, of Title 40,Code of Federal Regulations, as follows:

PART 425-[AMENDED]

1. The authority citation for Part 425 isrevised to read as follows:

Authority: Sections 301, 304(b), (c), (e), and(g), 306(b) and (c), 307(b) and (c), 308 and 501of the Clean Water Act (the Federal WaterPollution Control Act Amendments of 1972,as amended by the Clean Water Act of 1977(the "Act"); 33 U.S.C. 1311, 1314(b), (c), (e),and (g), 1316(b) and (c), 1317(b) and (c), 1318,and 1361; 86 Stat. 816, Pub. L. 92-500; 91 Stat.1567, Pub. L. 95-217.

General Provisions

2. Section 425.02 is amended byrevising paragraph (a) to read asfollows:

§ 452.02 General definitions.

(a) "Sulfide" shall mean total sulfideas measured by the potassiumferricyanide titration method describedin Appendix A or the modified Monier-Williams method described in AppendixB.

3. Section 425.03 is amended byrevising it to read as follows:

§ 425.03 Sulfide analytical methods andapplicability.

[a) The potassium ferricyanidetitration method described in AppendixA to Part 425 shall be used wheneverpracticable for the determination ofsulfide in wastewaters discharged byplants operating in all subcategoriesexcept the hair save or pulp, non-chrometan, retan-wet finish subcategory(Subpart C, see § 425.30). In all othercases, the modified Monier-Williamsmethod as described in Appendix B toPart 425 shall be used as an alternativeto the potassium ferricyanide titrationmethod for the determination of sulfidein wastewaters discharged by plantsoperating in all subcategories exceptSubpart C.

(b) The modified Monier-Williamsmethod as described in Appendix B toPart 425 shall be used for thedetermination of sulfide in wastewatersdischarged by plants operating in thehair save or pulp, non-chrome tan, retan-wet finish subcategory (Subpart C, see§ 425.30).

4. Section 425.04 is amended byadding paragraphs (d) and (e) to read asfollows:

§ 425.04 Applicability of sulfidepretreatment standards.

(d) (1) If, after EPA and the POTWhave determined in accordance with thissection that the sulfide pretreatmentstandards of this Part are not applicableto specified facilities, a POTW thendetermines that there have beenchanged circumstances (including butnot limited to changes in the factorsspecified in paragraph (b) of thissection) which justify application of thesulfide pretreatment standards, thePOTW shall revoke the certificationsubmitted under paragraph (c) of thissection. The POTW and EPA shall thenadhere to the general procedures andtime intervals contained in paragraph (c)of this section in order to determinewhether the sulfide pretreatmentstandards contained in this Part areapplicable.

(2) If pursuant to paragraph (d(1) ofthis section, the sulfide pretreatmentstandards of this Part are applicable to aspecified facility, the indirect dischargershall comply with the sulfidepretreatment standards no later than 18months from the date of publication ofthe Federal Register notice identifyingthe facility.

(e) At any time after October 13, 1983,if a POTW determines that there havebeen changed circumstances (includingbut not limited to changes in the factorsspecified in paragraph (b) of this

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Federal Register / Vol. 53, No. .54 / Monday, March 21, 1988 / Rules and Regulations

section), it may initiate proceedingscontained in paragraph (c) of thissection to determine that the sulfidepretreatment standards of this Part.shallnot be -applicable. The POTW .and EPAshall follow the procedures and timeintervals contained in paragraph ,(c) ofthis section to make this determination.A final determination that the sulfidepretreatment :standards are notapplicable must be made prior to thedischarge of sulfide not in accordancewith 'the standards set forth in this Part.

4a. Section 425.05 is revised to read asfollows:

§ 425.05 Compliance dates.The compliance date for new source

performance standards (NSPS) andpretreatment standards for new sources(PSES) is the date the new sourcecommences discharge. The Lcompliancedate forBPT effluent limitations andguidelines and pretreatment standardsfor existing sources to .no later thanMarch 31, 1989.

Subpart ,A-Hair Pulp, Chrome Tan,Retan-Wet Finish Subcategory

5. Section 425.11 is amended byrevising the table of BPT limitations toread as follows:

§ 425.11 Effluent limitations representingthe degree of effluent reduction attainableby the application of the best practicablecontrol technology currently available(BPT).

-BPT limitations

Pollutant or pollutantproperty .Maximum for' Maximum for

any 1 day monthlyI average

.kg/kkg (or pounds per1,000 pounds of raw ma-terial

BOD5................. 9.3 4.2TSS ................................ 13.4 6.1Oil & Grease .................. 3.9 1.7Total Chromium 0....... 0.24 0.09pH .................................. (') (')

I Within the range of 6.0 to 9.0

6. Section 425.15 is amended byrevising paragraph (b) to read asfollows:

§ 425.15 Pretreatment standards forexisting sources (PSES).

(b) Any existing source subject to thissubpart which processes less than 275hides/day shall comply with § 425.15(a),except ,that the total chromiumlimitationscontained in § 425.15(a) donot apply.

Subpart C-Hair Save or Pulp, Non-Chrome Tan, Retan-Wet FinishSubcategory



BPT limitationsPollutant or pollutant aximum fo

property Maximum for Mamonthlymonralyany 1 day average

kg/kkg (or pounds per1,000 pounds) of raw material

BOD5 ............................. 6.7 3.0TSS ................................. 9.7 4.4Oil & Grease .................. 2.8 1.3Total Chromium ............ 0.17 0.06pH ................................... ... (I) (I)

'Withiii the range of 6.0 to 90

8. Section 425.35 is amended byrevising the table of PSES standards inparagraph (a) and revising pagaraph (b)to read as follows:§ 425.35 Pretreatment standards forexisting sources (PSES).

(a) * * *

PSES limitationsPollutant or pollutant Maximum Maximum

property for any 1 for monthlyday average

Milligrams per liter (mg/I)

Sulfide ............. ............. . 24 -Total Chromium .............. 12 6pH ................................... . () ()

'Not less than 7.0.

(b) Any existing source subject to thissubpart which processes less than 350hides/day shall comply with § 425.35(a),except that the Total Chromiumlimitations contained in § 425.35(a) donot apply.

Subpart D-Retan-Wet Finish-SidesSubcategory

9. Section 425.41 is amended byrevising the section heading and thetable of BPT limitations to read asfollows:

§ 425.41 Effluent limitations representingthe degree of effluent reduction attainableby the application of the best practicablecontrol technology currently available(BPT).. * * * *

BPT limitations

Pollutant.or pollutant Maximum forproperty -Maximum for monthly

any 1 day average

kg/kkg (or pounds per1,000 pounds) of raw ma-terial

BOD5 ............. ............ 8.9 4.DTSS ................. ........... 12.8 5.8Oil &.Grease 3.................. 37 1.7Total Chromium ........... 0.23 0.08pH .................................. (') ')

'Within the range of 6.0 to 9.0.

10. Section 425.44 is amended .byrevising the table of NSPS to .read asfollows:§ 425.44 New source performance

standards.(NSPS).

*r * * * *

NSPS

Pollutant or pollutant Maximum forproperty Maximum for Maimforany 1 day monthlyag

average

kg/kkg .(or pounds per1,000 pounds) of raw ma-terial

BOD5 ............................. 6.5 2.9TSS ................................ 9.3 4.3Oil & Grease .................. 2.7 1.2Total Chromium ............ 0.17 0.06pH ..... : ................ t .......... (1) (,)

'Within the range of 6.0 to'9.0.

Subpart E-No BeamhouseSubcategory



BPT limitations

Pollutant or pollutant Maximum forproperty Maximum for monthly

any 1 day average

kg/kkg .(or pounds per1,000 pounds) of raw ma-terial

BOD ............................. 8.0 3.6TSS ........................ 11.6 5.3Oil & Grease .................. 3.4 1.5

'Total Chromium 0.21 0.08

pH .................................. (I) (1)

IWithin the range of ,6.0 to 9.0.

9182


Subpart F-Through-the-BlueSubcategory



BPT limitationsPollutant or pollutant Maximum for

property Maximum f monthlyany 1 day average


BOD5 .................. 3.2 1.5TSS ................................. 4.7 2.1Oil & Grease .................. 1.4 0.61Total Chromium ............ 0.08 0.03pH ................................... (1) (1)


13. Section 425.64 is amended byrevising the table of NSPS to read asfollows:

§ 425.64 New source performancestandards (NSPS).

NSPSPollutant or pollutant Maximum for

property Maximum for monthlyany I day monthlyaverage


BODS ............................. 3.0 1.3TSS ................................. 4.3 1.9Oil & Grease .................. 1.2 0.55Total Chromium ............ 0.08 0.03pH ................................... (1) (1)

Within the range of 6.0 to 9.0.

Subpart G-Shearling Subcategory



BPT limitationsPollutant or pollutant Maximum for

property Maximum for monthlyany 1 day average


BO D5 ............................. 15.0 6.8TSS ................................. 21.7 9.9Oil & Grease .................. 6.3 2.8Total Chromium ............ 0.39 0.14pH ................................... (1) (1)


Subpart I-Retan-Wet Finish-SplitsSubcategory



BPT limitationsPollutant or pollutant

property Maximum for Maximum forany I day monthly

average


BO D5 ............................. 5.8 2.6TSS ................................. 8.3 3.8Oil & Grease .................. 2.4 1.1Total Chromium ............ 0.15 0.05pH ................................... (1) (1)


16. Section 425.95 is amended byrevising paragraph (b) to read asfollows:

§ 425.95 Pretreatment standards forexisting sources (PSES).

(b) Any existing source subject to thissubpart which processes less than 3,600

splits/day shall comply with § 425.95(a),except that the total chromiumlimitations contained in § 425.95(a) donot apply.

17. Part 425 is amended by addingAppendix A to read as follows:

Appendix A to Part 425-PotassiumFerricyanide Titration Method

SourceThe potassium ferricyanide titration

method is based on method SLM 4/2described in "Official Method of Analysis,"Society of Leather Trades' Chemists, FourthRevised Edition, Redbourn. Flerts., England.1965.

Outline of MethodThe buffered sulfide solution is titrated

with standard potassium ferricyanidesolution in the presence of a ferrousdimethylglyoxime ammonia complex. Thesulfide is oxidized to sulfur. Sulfite interferesand must be precipitated with bariumchloride. Thiosulfate is not titrated under theconditions of the determination (Chariot,"Ann. chim, anal,". 1945, 27, 153; Booth; "J.Soc. Leather Trades' Chemists," 1956, 40,238).

ApparatusBurrette, 10 ml.

Reagents1. Preparation of 0.02N potassium

ferricyanide; Weigh to the nearest tenth of agram 6.6 g. of analytical reagent gradepotassium ferricyanide and dissolve in 1 literdistilled water. Store in an amber bottle inthe dark. Prepare fresh each week.

2. Standardization of ferricyanide solution:Transfer 50 ml. of solution to a 250 ml.Erlenmeyer flask. Add several crystals ofpotassium iodide (about 1 g.), mix gently todissolve, add 1 ml. of 6N hydrochloric acid,stopper the flask, and swirl gently. Let standfor two minutes, add 10 ml. of a 30 percentzinc sulfate solution, and titrate the mixturecontaining the gelatinous precipitate with.standardized sodium thiosulfate orphenylarsine oxide titrant in the range of0.025-0.050N Add 1 ml. of starch indicatorsolution after the color has faded to a paleyellow, and continue the titration to thedisappearance of the blue color. Calculate thenormality of the ferricyanide solution usingthe equation:

9183


Normality of Potassium Ferricyanide [KsFe(CNkI = (ml of thiosulfate added) (normality of thiosulfate)

MI of KjFe(CN)

3. Preparation of 6M ammonium chloridebuffer, pH 9.3: Dissolve 200 g. ammoniumchloride in approximately 500 ml. distilledwater, add 200 ml. 14M reagent gradeammonium hydroxide and make up to I literwith distilled water. The buffer should beprepared in a hood. Store in a tightlystoppered container.

4. Preparation of 0.05M barium chloridesolution: Dissolve 12-13 g. barium chloridedihydrate in I liter of distilled water.

5. Preparation of ferrous dimethylglyoximeindicator solution: Mix 10 ml. 0.6 percentferrous sulfate, 50 ml. 1 percentdimethylglyoxime in ethanol, and 0.5 ml.concentrated sulfuric acid.

6. Preparation of stock sulfide standard,1000 ppm: Dissolve 2.4 g. reagent gradesodium sulfide in 1 liter of distilled water.Store in a tightly stoppered container. Dilutedworking standards must be prepared freshdaily and their concentrations determined byEPA test procedure 376.1 (see 40 CFR 136.3,Table lB, parameter 66 (49 FR 43234, October26, 1984, with correction notice at 50 FR 690,January 4, 1985)) immediately prior to use.

7. Preparation of ION NaOH: Dissolve 400g. of analytical reagent grade NaOH in 1 literdistilled water.

Sample Preservation and Storage

Samples are to be field filtered (gravity orpressure) with coarse filter paper (Whatman4 or equivalent) immediately after collection.Filtered samples must be preserved byadjustment to pH> 12 with ION NaOH.Sample containers must be covered tightlyand stored at 4 °C until analysis. Samplesmust be analyzed within 48 hours ofcollection. If these procedures cannot beachieved, it is the laboratory's responsibilityto institute quality control procedures thatwill provide documentation of sampleintegrity.

Procedure

1. Transfer 100 ml. of sample to beanalyzed, or a suitable portion containing notmore than 15 mg. sulfide supplemented to 100ml. with distilled water, to a 250 ml.Erlenmeyer flask.

2. Adjust the sample to pH 8.5-9.5 with 6NHC1.

3. Add 20 ml. of 6M ammonium chloridebuffer (p1i 9.3), 1 ml. of ferrousdimethylglyoxime indicator, and 25 ml. of0.05M barium chloride. Mix gently, stopper,and let stand for 10 minutes.

4, After 10 minutes titrate withstandardized potassium ferricyanide todisappearance of pink color. The endpoint is

reached when there is no reappearance of thepink color after 30 seconds.

Calculation and Reporting of Results.

1. mg./l sulfide =A x B x 16,000

vol. in ml. ofsample titrated

where A=volume in ml. of potassiumferricyanide solution used,

and B=normality of potassium ferricyanidesolution.

2. Report results to two significant figures.

Quality Control

1. Each laboratory that uses this method isrequired to operate a formal quality controlprogram. The minimum requirements of thisprogram consist of an initial demonstration oflaboratory capability and the analysis ofreplicate and spiked samples as a continuingcheck on performance. The laboratory isrequired to maintain performance records todefine the quality of data that is generated.Ongoing performance checks must becompared with established performancecriteria to determine if the results of analysesare within precision and accuracy limitsexpected of the method.

21 Before performing any analyses, theanalyst must demonstrate the ability togenerate acceptable precision and accuracywith this method by performing the followingoperations.

(a) Perform four replicate analyses of a 20mg./l. sulfide standard prepared in distilledwater (see paragraph 6 under "Reagents"above).

(b)(1) Calculate clean water precision andaccuracy in accordance with standardstatistical procedures. Clean wateracceptance limits are presented in paragraph2(b)(2) below. These criteria must be met orexceeded before sample analyses can beinitiated. A clean water standard must beanalyzed with each sample set and theestablished criteria met for the analysis to beconsidered under control.

(2) Clean water precision and accuracyacceptance limits: For distilled water samplescontaining from 5 mg./I. to 50 mg./I. sulfide,the mean concentration from four replicateanalyses must be within the range of 50 to110 percent of the true value.

3. The Method Detection Limits (MDL)should be determined periodically by eachparticipating laboratory in accordance withthe procedures specified in "Methods for

Chemical Analysis of Municipal andIndustrial Wastewater," EPA-660/4-82-057,July 1982, EMSL, Cincinnati, OH 45268. Forthe convenience of the user, these proceduresare contained in Appendix C to Part 425.

4. A minimum of one spiked and oneduplicate sample must be performed for eachanalytical event, or five percent spikes andfive percent duplicates when the number ofsamples per event exceeds twenty. Spikelevels are to be at the MDL (see paragraph 3above for MDL samples) and at x where x isthe concentration found if in excess of theMDL. Spike recovery must be 40 to 120percent for the analysis of a particular matrixtype to be considered valid. If a sample ormatrix type provides performance outsidethese acceptance limits, the analyses must berepeated using the modified Monier-Williamsprocedures described in Appendix B to thisPart.

5. Report results in meg./liter. Whenduplicate and spiked samples are analyzed,report all data with the sample results.

18. Part 425 is amended by addingAppendix B to read as follows:

Appendix B to Part 425-t MdifiedMonier-Williams Method

Outline of Method

Hydrogen sulfide is liberated from anacidified sample by distillation and purgingwith nitrogen gas (N2). Sulfur dioxide• interference is removed by scrubbing thenitrogen gas stream in a pH 7 buffer solution.-The sulfide gas is collected by passagethrough an alkaline hydrogen peroxidescrubbing solution in which it is oxidized tosulfate. Sulfate concentration in thescrubbing solution is determined by eitherEPA gravimetric test procedure 375.3 or EPAturbidimetric test procedure 375.4 (see 40 CFR136.3, Table I1, parameter 65 (49 FR 43234,October 26, 1984, and correction notice at 50FR 690, January 4, 1985)).

Apparatus *

(See Figure 1.) * Catalogue numbers aregiven only to provide a more completedescription of the equipment necessary, anddo not constitute a manufacturer or vendorendorsement.

Heating mantel and control (VWR Cat. No.33752-464)

1000 ml. distilling flask with three 24/40joints (VWR Cat. No. 29280-215)

Friedricks condenser with two 24/40 joints(VWR Cat. No. 23161-009)

BILLING CODE 6560-50-M

9184


FIGURE 1EQUIPMENT ASSEMBLY

ADAPTER JOINT

125 mlSEPARATORYFUNNEL

INLETTUBE

HEATING MANTLE

BILLING CODE 6560-50-C

a I 1-rql R.


125 ml. separatory funnel with 24/40 joint(VWR Cat. No. 30357-102)

Inlet tube with 24/40 joint (VWR Cat. No.33057-105)

Adapter joint 24/40 to 19/38 (VWR Cat. No.62905-26)

Adsorber head (2 required) (Thomas Cat. No.9849-R29)

Adsorber body (2 required) (Thomas Cat. No.9849-R32)

Laboratory vacuum pump or water aspirator

Reagents1. Potassium hydroxide, 6N: Dissolve 340 g.

of analytical reagent grade KOH in 1 literdistilled water.

2. Sodium hydroxide, 6N: Dissolve 240 g. ofanalytical reagent grade NaOH in I literdistilled water.

3. Sodium hydroxide, 0.03N: Dilute 5.0 ml.of 6N NaOH to I liter with distilled water.

4. Hydrochloric acid, 6N: Dilute 500 ml. ofconcentrated HCI to 1 liter with distilledwater.

5. Potassium phosphate stock buffer, O.5M:Dissolve 70 g. of monobasic potassiumphosphate in approximately 800 ml. distilledwater. Adjust pH to 7.0 L 0.1 with 6Npotassium hydroxide and dilute to 1 liter withdistilled water. Stock solution in stable forseveral months at 4 *C.

6. Potassium phosphate buffer, 0.05M:Dilute 1 volume of O.5M potassium phosphatestock buffer with 9 volumes of distilled water.Solution is stable for one month at 4 *C.

7. Alkaline 3% hydrogen peroxide: Dilute 1volume of 30 percent hydrogen peroxide with9 volumes of 0.03N NaOH. Prepare thissolution fresh each day of use.

8. Preparation of stock sulfide standard,1000 ppm.: Dissolve 2.4 g. reagent gradesodium sulfide in 1 liter of distilled water.Store in a tightly stoppered container. Dilutedworking standards must be prepared freshdaily and their concentrations determined byEPA test procedure 376.1 immediately prior touse (see 40 CFR 136.3, Table IB, parameter 66(49 FR 43234, October 26,-1984, and correctionnotice at 50 FR 690, January 4, 1985)).

Sample Preservation and StoragePreserve unfiltered wastewater samples

immediately after collection by adjustment topH>9 with_6N NaOH and addition of 2 ml. of2N zinc acetate per liter. This amount of zincacetate is adequate to preserve 64 mg./I.sulfide under ideal conditions. Samplecontainers must be covered tightly and storedat 4 °C until analysis. Samples must beanalyzed within seven days of collection. Ifthese procedures cannot be achieved, it is thelaboratory's responsibility to institute qualitycontrol procedures that will providedocumentation of sample integrity.

Procedure (See Figure 1 for apparatuslayout.)

1. Place 50 ml. of 0.05M pH 7.0 potassiumphosphate buffer in Trap No. 1.

2. Place 50 ml. of alkaline 3 percenthydrogen peroxide in Trap No. 2.

3. Sample introduction and N2 prepurge:Gently mix sample to be analyzed toresuspend settled material, taking care not toaerate the sample. Transfer 400 ml. of sample,or a suitable portion containing not morethan 20 mg. sulfide diluted to 400 ml. with

distilled water, to the distillation flask.Adjust the N2 flow so that the impingers arefrothing vigorously, but not overflowing.Vaccum may be applied at the outlet of TrapNo. 2 to assist in smooth purging. The N2 inlettube of the distillation flask must besubmerged deeply in the sample to ensureefficient agitation. Purge the sample for 30minutes without applying heat. Test theapparatus for leaks during the prepurge cycle(Snoop or soap water solution).

4, Volatilization of H2S: Interrupt the N2flow (and vacuum) and introduce 100 ml. of6N HCI to the sample using the separatoryfunnel. Immediately resume the gas flow (andvacuum). Apply maximum heat with theheating mantle until the sample begins toboil, then reduce heat and maintain gentleboiling and N2 flow for 30 minutes. Terminatethe distillation cycle by turning off theheating mantle and maintaining N2 flowthrough the system for 5 to 10 minutes. Thenturn off the N2 flow (and release vacuum) andcautiously vent the system by placing 50 to100 ml. of distilled water in the separatoryfunnel and opening the stopcock carefully.When the bubbling stops and the system isequalized to atmospheric pressure, removethe separatory funnel. Extreme care must beexercised in terminating the distillation cycleto avoid flash-over, draw-back, or violentsteam release.

5. Analysis: Analyze the contents of TrapNo. 2 for sulfate according to either EPAgravimetric test procedure 375.3 or EPAturbidimetric test procedure 375.4 (see 40 CFR136.3, Table IB, parameter 65 (49 FR 43234,October 26, 1984, and correction notice at 50FR 690, January 4, 1985)). Use the result tocalculate mg./I. of sulfide in wastewatersample.

Calculations and Reporting of Results

1. Gravimetric procedure:

S(mg. BaSO 4

collected in TrapNo. 2)X (137)mg sulfide/I. = volume in ml. ofwaste sample

distilled

2. Turbidimetric procedure:

AxBx333mg. sulfide/I. = C

where A=mg./l. of sulfate in Trap No. 2B=liquid volume in liters in Trap No. 2and C=volume in ml. of waste sample

distilled

3. Report results to two significant figures.

Quality Control

1. Each laboratory that uses this method isrequired to operate a formal quality controlprogram. The minimum requirements of thisprogram consist of an initial demonstration oflaboratory capability and the analysis of.replicate and spiked samples as a continuingcheck on performance. The laboratory isrequired to maintain performance records to

define the quality of data that is venerated.Ongoing performance checks must becompared with established performancecriteria to determine if the results of analysesare within precision and accuracy limitsexpected of the method.

2. Before performing any analyses, theanalyst must demonstrate the ability togenerate acceptable accuracy and precisionby performing the following operations.

(a) Perform four replicate analyses of a 20mg./I. sulfide standard prepared in distilledwater (see paragraph 8 under "Reagents"above).

(b)(1) Calculate clean water precision andaccuracy in accordance with standardstatistical procedures. Clean wateracceptance limits are presented in paragraph2(b)(2) below. These criteria must be met orexceeded before sample analyses can beinitiated. A clean water standard must beanalyzed with each sample set and theestablished criteria met for the analyses to beconsidered under control.

(2) Clean water precision and accuracyacceptance limits: For distilled water samplescontaining from 5 mg./. to 50 mg/I. sulfide,the mean concentration from four replicateanalyses must be within the range of 72 to114 percent of the true value.

3. The Method Detection Limit (MDL)should be determined periodically by eachparticipating laboratory in accordance with

-the procedures specified in "Methods forChemical Analysis of Municipal andIndustrial Wastewater," EPA-600/4--82-057,July 1982, EMSL, Cincinnati, OH 45268. Forthe convenience of the user, these proceduresare contained in'Appendix C to Part 425.

4. A minimum of one spiked and oneduplicate sample must be run for eachanalytical event, or five percent spikes andfive percent duplicates when the number ofsamples per event exceeds twenty. Spikelevels are to be at the MDL (see paragraph 3above for MDL samples) and at x when x isthe concentration found if in excess of theMDL. Spike recovery must be 60 to 120percent for the analysis of a particular matrixtype to be considered valid.

5. Report all results in mg./liter. Whenduplicate and spiked samples are analyzed,report all data with the sample results.

19. Part 425 is amended by addingAppendix C to read as follows:

Appendix C to Part 425-Definition andProcedure for the Determination of theMethod Detection Limit

The method detection limit (MDL) isdefined.at the minimum concentration of asubstance that can be identified, measuredand reported with 99 percent confidence thatthe analyte concentration is greater than zeroand determined from analysis of a sample ina given matrix containing analyte.

Scope and Application

This procedure is designed for applicabilityto a wide variety of sample types ranging

Source: "Methods for Chemical Analysis ofMunicipal and Industrial Wastewater," EPA-600/4-82-057, July 1982, EMSL, Cincinnati, OH 45268

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Federal Register /. Vol. 53, No. 54 / Monday, March 21, 1988 / Rules and Regulations

from reagent (blank) water containinganalyte to wastewater containing analyte.The MDL for an analytical procedure mayvary as a function of sample type. Theprocedure requires a complete, specific andwell defined analytical method. It is essentialthat all sample processing steps of theanalytical method be included in thedetermination of the method detection limit.

The MDL obtained by this procedure isused to judge the significance of a singlemeasurement of a future sample.

The MDL procedure was designed forapplicability to a broad variety of physicaland chemical methods. To accomplish this,the procedure was made device- orinstrument-independent.

Procedure

1. Make an estimate of the detection limitusing one of the following:

(a) The concentration value thatcorresponds to an instrument signal/noiseratio in the range of 2.5 to 5. If the criteria forqualitative identification of the analyte isbased upon pattern recognition techniques,the least abundant signal necessary toachieve identification must be considered inmaking the estimate.

(b) The concentration value thatcorresponds to three times the standarddeviation of replicate instrumentalmeasurements for the analyte in reagentwater.

(c) The concentration value thatcorresponds to the region of the standardcurve where there is a significant change insensitivity at low analyte concentrations, i.e..a break in the slope of the standard curve.

(d) The concentration value thatcorresponds to known instrumentallimitations.

It is recognized that the experience of theanalyst is important to this process.However, the analyst must include the aboveconsiderations in the estimate of thedetection limit.

2. Prepare reagent (blank) water that is asfree of analyte as possible. Reagent orinterference free water is defined as a watersample in which analyte and interferentconcentrations are not detected at themethod detection limit of each analyte ofinterest. Interferences are defined assystematic errors in the measured analyticalsignal of an established procedure caused bythe presence of interfering species(interferent). The interferent concentration ispresupposed to be normally distributed inrepresentative samples of a given matrix.

3. (a) If the MDL is to be determined inreagent water (blank). prepare a laboratorystandard (analyte in reagent water) at aconcentration which is at least equal to or inthe same concentration range as theestimated MDL. (Recommended between 1and 5 times the estimated MDL.) Proceed toStep 4.

(b) If the MDL is to be determined inanother sample matrix, analyze the sample. Ifthe measured level of the analyte is in therecommended range of one to five times theestimated MDL, proceed to Step 4.

If the measured concentration of analyte isless than the estimated MDL, idd a knownamount of analyte to bring the concentration

of analyte to between one and five times theMDL. In the case where an interference iscoanalyzed with the analyte:

If the measured level of analyte is greaterthan five times the estimated MDL, there aretwo options:

(1) Obtain another sample of lower level ofanalyte in same matrix if possible.

(2) The sample may be used as is fordetermining the MDL if the analyte level doesnot exceed 10 times the MDL of the analyte inreagent water. The variance of the analyticalmethod changes as the analyte concentrationincreases from the MDL, hence the MDLdetermined under these circumstances maynot truly reflect method variance at loweranalyte concentrations.

4. (a] Take a minimum of seven aliquots ofthe sample to be used to calculate the MDLand process each through the entireanlaytical method. Make all computationsaccording to the defined method with finalresults in the method reporting units. If blankmeasurements are required to calculate themeasured level of analyte, obtain separateblank measurements for each sample aliquotanlayzed. The average blank measurement issubtracted from the respective samplemeasurements.(b) It may be economically and technically

desirable to evaluate the estimated MDLbefore proceeding with 4a. This will: (1)Prevent repeating this entire procedure whenthe costs of analyses are high and (2) insurethat the procedure is being conducted at thecorrect concentration. It is quite possible thatan incorrect MDL can be calculated fromdata obtained at many times the real MDLeven though the background concentration ofanalyte is less than five times the calculatedMDL. To insure that the estimate of the MDLis a good estimate, it is necessary todetermine that a lower concentration ofanalyte will not result in a significantly lowerMDL. Take two aliquots of the sample to beused to calculate the MDL and process eachthrough the entire method, including blankmeasurements as described above in 4a.Evaluate these data:(1) If these measurements indicate the

sample is in the desirable range fordetermining the MDL, take five additionalaliquots and proceed. Use all sevenmeasurements to calculate the MDL.

(2) If these measurements indicate thesample is not in the correct range, reestimate,the MDL, obtain new sample as in 3 andrepeat either 4a or 4b.

5. Calculate the variance (S9 and standarddeviation (S) of the replicate measurements,as follows:

n n

S 2 .1 [E. X (1 X±)n=n-1 X-1i " Y

S = (S2 )0 .5

where: the xj, i = 1 to n are the analyticalresults in the final method reporting unitsobtained from the n sample aliquots and

x2

i-i

refers to the sum of the X values from i = 1 ton.

6. (a] Compute the MDL as follows:MDL = t(n-1. - = . 9) (S)where:MDL= the method detectiont(n-1, I-a=.99)=the students' I value

appropriate for a 99 percent confidencelevel and a standard deviation estimatewith n-1 degrees of freedom. See Table.

S=standard deviation of the replicateanalyses.

(b) The 95 percent confidence limits for theMDL derived in 6a are computed according tothe following equations derived frompercentiles of the chi square over degrees offreedom distribution (X2/df] and calculatedas follows:MDLLCL=0.69 MDLM DLUcL=1.92 MDL where MDLLCL and

MDLUCL are the lower and upper 95percent confidence limits respectivelybased on seven aliquots.

7. Optional iterative procedure to verify thereasonableness of the estimated MDL andcalculated MDL of subsequent MDLdeterminations.

(a) If this is the initial attempt to computeMDL based on the estimated MDL in Step 1.take the MDL as calculated in Step 6, spike inthe matrix at the calculated MDL andproceed through the procedure starting withStep 4.

(b) If the current MDL determination is aniteration of the MDL procedure for which thespiking level does not permit qualitativeidentification, report the MDL as thatconcentration between the current spike leveland the previous spike level which allowsqualitative identification.

(c) If the current MDL determination is aniteration of the MDL procedure and thespiking level allows qualitative identification,use S2 from the current MDL calculation andS2 from the previous MDL calculation tocompute the F ratio.

2SA

if -- 2 < 3.05SB

then compute the pooled standard deviationby the following equation:

Spooled [2 ]

9187

9188 Federal Register / Vol. 53, No. 54 / Monday, March 21, 1988 / Rules and Regulations2

S2SA

if S >3.05,SB

respike at the last calculated MDL andprocess the samples through the.procedurestarting with Step 4.

(d) Use the Sr.oId as calculated in 7b tocompute the final MDL according to thefollowing equation:MDL=2.681 (Spooled)where 2.681 is equal to 1(12, 1-a =.99)

(e) The 95 percent confidence limits forMDL derived in 7c are computed according tothe following equations derived frompercentiles of the chi squared over degrees offreedom distribution.

MDLLcL= 0.72 MDLMDLucL = 1.65 MDL

where LCL and UCL are the lower and upper95 percent confidence limits respectivelybased on 14 aliquots.

Reporting

The analytical method used must bespecifically identified by number or title andthe MDL for each analyte expressed in theappropriate method reporting units. If theanalytical method permits options whichaffect the method detection limit, theseconditions must be specified with the MDLvalue. The sample matrix used to determinethe MDL must also be identified with theMDL value. Report the mean analyte levelwith the MDL. If a laboratory standard or asample that contained a known amountanalyte was used for this determination,report the mean recovery, and indicate if theMDL determination was iterated.

If the level of the analyte in the samplematrix exceeds 10 times the MDL of theanalyte in reagent water, do not report avalue for the MDL.

Reference

Glaser, J.A., Foerst, D.L., McKee, G.D.,Quave, S.A., and Budde, W.L., "Trace

Analysis for Wastewaters," EnvironmentalScience and Technology, 15, 1426 (1981).

TABLE OF STUDENTS' t VALUES AT THE 99PERCENT CONFIDENCE LEVEL

DegreesNumber of replicates of (n-1,

freedom 1 -a =.99)(n-1)

7 ....................................... 6 3 .14 38 ....................................... 7 2.9989 ........................................ 8 2.89610 ...................................... 9 2.82111 ........... ........................ 10 2.76416 ...................................... 15 2.6022 1 ...................................... 20 2.52826 ...................................... 25 .2.48531 ...................................... 30 2.45761 ...................................... 60 2.390

2.326

[FR Doc. 88-5722 Filed 3-18-88; 8:45 am]

BILLING CODE 6560-50-M

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