Guidelines for CEMS Performance Specifications

and Quality Assurance Requirements for Municipal Waste Combustion Facilities

September 1990

U.S. EPA Contract No. 68D90055 Work Assignments 15 and 37

Prepared by:

James W. Peeler CEM/Engineering Division Entropy Environmentalists, Inc. Research Triangle Park, North Carolina 27709

Prepared for:

Nancy Seidman Northeast States for Coordinated Air Use Management

By agreement with:

Emission Measurement Branch Technical Support Division U.S. Environmental Protection Agency Research Triangle Park, North Carolina 27711ACKNOWLEDGEMENTS

This guideline document is based on discussions of a workgro up organizedby the Northeast States for Coordinated Air Us e Mana gement (NESCAUM). The workgroup was created to provid e guidance t o state and local agencies which use or plan to us e continuous emission monitoring systems (CEMS) to determin e comp liance at municipal waste combustion (MWC) facilities. Th e guid elines are intended to promote consistency in designing an d
oper ating CEMS and reporting monitoring data. The documen t reflects the recommendations of state and federal agency sta ff. In addition, a draft of these guidelines was distributed to othe r ag encies, CEM equipment vendors, and MWC owners and operators

. Their comments and suggestions were reviewed and discussed by the workgroup and appropriate changes were made to the guidelines. Thi s project was funded by the NESCAUM states, the U S Envi ronmental Protection Agency Regional Offices in Boston, Ne w Yor k, and Philadelphia, the Stationary Source Compliance an d Techni cal Support Divisions of the US Environmental Protectio n Agency's Office of Air Quality Planning and Standards, and the US Environmental Protection Agency's Office of Research an d Deve lopment in the Atmospheric Research and Exposure Assessmen t Laborat ory. We thank all of the people who helped fund thi s project. The workgroup was organized and managed by Nancy L. Seidman, Special Projects Director of NESCAUM. The workgroup members were drawnfrom state and federal agencies. The members of th e workgroup are listed below. Cal ifornia Air Resources Board - Robert Fletcher, Pete r Ouchida Connecticut Bureau of Air Mana gement - Carl Dodge, Mark Peak, Joe Ulevicus Maine Bureau of Air Quality Control - Jane Longfellow, Scott Mason Massac husetts Division of Air Quality Control - Ed Braczyk
, Robert Quevillon, William Sullivan New Hampshire Air Resources Division - Andrew Bodnarik, Jack Glenn New Jersey Division of Environmental Quality - Ed Choromansk i, Don Patterson New Yo rk Division of Air Resources - Frank Buckman, Rober t Kerr, Tim Ross NESCAUM - Nancy Seidman Ohio Division of Air Pollution Control - Tammy Hilkens Pennsylvania Bureau of Air Quality Control - Joe Nazzaro Vermont Air Pollution Control Division - Brian Fitzgerald

U.S. Environmental Protection Agency Region I, Boston - Tom Elter, Mary Ellen Stanton Region II, New York - Ann ZownirRegion II, Philadelphia - Robert Vollaro

Offi ce of Air Quality Planning and Standards, Stationary Sourc e Compliance Division - Louis Paley Offi ce of Air Quality Planning and Standards, Technical Suppor t Division - Terry Harrison, Gil Wood Office of Research and Development, Atmospheric Research and th e Exposure Assessment Laboratory - Tom Logan Jame s W. Peeler and George W. Walsh of Entrop y Environmentalists, Inc. partic ipated in workgroup meetings, helped direct the efforts of the workgroup, and prepared this document. We gratefully acknowledge the time invested by the workgroup. Their assistance and expertise made this project possible.CONTENTS

Page

Section 1 SUMMARY 1

Section 2 PERFORMANCE SPECIFICATIONS FOR SO2 AND NOx CEMS 7 AT MUNICIPAL WASTE COMBUSTION FACILITIES

Section 3 PERFORMANCE SPECIFICATIONS FOR CO CEMS 15 AT MUNICIPAL WASTE COMBUSTION FACILITIES

Section 4 PERFORMANCE SPECIFICATIONS FOR HCl CEMS 21 AT MUNICIPAL WASTE COMBUSTION FACILITIES

Section 5 QUALITY ASSURANCE REQUIREMENTS FOR SO2, NOx, 25 CO, AND HCl CEMS

Section 6 EQUIPMENT AND PERFORMANCE SPECIFICATIONS FOR 33 OPACITY CEMS AT MUNICIPAL WASTE COMBUSTION FACILITIES

Section 7 QUALITY ASSURANCE REQUIREMENTS FOR OPACITY CEMS 37

Appendix Comparison of Accuracy SpecificationsSECTION 1 -- SUMMARY

This guideline document is based on discussions of a workgro up organizedby the Northeast States for Coordinated Air Us e Mana gement (NESCAUM). The workgroup was created to provid e guidance t o state and local agencies which use or plan to us e continuous emission monitoring systems (CEMS) to determin e comp liance at municipal waste combustion (MWC) facilities. Th e guid elines are intended to promote consistency in designing an d
oper ating CEMS and reporting monitoring data. The documen t reflects the recommendations of state and federal agency sta ff. In addition, a draft of these guidelines was distributed to othe r ag encies, CEM equipment vendors, and MWC owners and operators

. Their comments and suggestions were reviewed and discussed by the workgroup and appropriate changes were made to the guidelines. The N ESCAUM recommendations reflect a consensus of th e workgroup participants arrived at through discussions durin g
sev eral meetings. The resulting recommendations reflect th e coll ective experience, opinions, and judgement of the workgrou p participants from the regulato ry agency perspective. The scope of this project did not include the acquisition or analysis of data or other information to serve as the basis for specific requirements or recommendations. The NE SCAUM workgroup recommends that states adopt regulation s which require the use of CEMS to determine compliance with e mission standards on a continuous basis at MWC facilities. The regu lations should: · Establish initial certifica tion procedures and requirements for CEMS

· Define quality assurance (QA) procedures and criteria for th e ongoing determination of the acceptability of the CEMS and th e monitoring data · Specify minimum data capture requirements The CE MS requirements in 40 CFR 60, including 60.1 3 "Monitoring requirements", Appendix B - Performance Specific ations, and Appendix F - Quality Assurance Procedures are recommended as

a w orking base for state regulations. The federal requirements
, how ever, are recognized as the minimum needed to ensure reliabl e CEMS p erformance and acceptable emissions data. The federa l regulations have not been recently revised to keep up with th e evolution of CEM technology. Recommendations are included here to address problems encountered in actual practice which are no t adequatelyresolved by the existing federal regulations. Th e recommendations are specifical ly designed for CEMS programs at MWC facilities and they attempt to address technical issues that may be encountered in the implementation of monitoring programs sub ject to

a wide variety of state regulations. It is hoped that thes e recommendations will facilitate a more consistent approach i n stateCEMS programs and requirements.

State requirements for emission standards, percent remova l requirements, averaging times, and reporting may diffe r subst antiallyfrom the EPA New Source Performance Standard s currently being developed. Significant differences among th e various state regulations are also likely. Therefore, the NESCAUM workgroup recommendations for performance specifications an d quality assurance procedures a re presented in general terms rather than i n specific regulatory language. States desiring to adop t these recommendations will need to make appropriate modifications to them so that they are compatible with the applicable emissio n standa rds and other existing regulations. Specific language fo r requirements based on the modified recommendations and th e ref erenced federal regulations will also need to be developed by each state agency. The following sections of this document present detaile d recommendations for performance specifications and qualit y
assurance requirements for gas and opacity CEMS. Many of th e spe cifications are expressed in terms of "percent of span" sinc e the actual measurement range of the instrumentation should b e specified by the state agency to be compatible with the applicable regulations and enforcement policies. In specifying the spa n value, the agency should consider trade-offs between an expande d measurement range and more accurate data at typical emissionlevels or at the level of the emission standard. Some factors to c onsider inspecifying the span value include: the applicable emissio n standard or percent removal requirement, the averaging time for the standard, the inherent variability of uncontrolled and controlled emissi ons during normal operation and during malfunctions of th e facility, and the actions to b e taken by the agency and the source owner or operator if emissions exceed the measurement range of the CEMS. The recommendations presented in this document were developed for MWC facilities. Many of these recommendations could also b e appli edto other sources; however, no attempt was made in thi s project to identify or address the specific technical an d
regu latoryissues associated with CEMS programs at other sourc e categories. These issues include:

· pro cedures used to convert gas concentration measurements t o units of the standard,

· emissions variability associated with the process and contro l equipm ent and the corresponding averaging time for CEMS dat a recording and reporting and de termining compliance with applicable standards,

· likelihood of substances within the effluent stream causin g analytical interferences with either CEMS measurements or re ference measurements used for relative accuracy determinations

· effluent conditions such as temperature, pressure, moistur e
con tent, and the presence of other materials within the effluen t stre amthat may affect the operation and reliability o finstrumentation.

Carefu l consideration of these and other issues is warranted i n apply ing the recommendations presented here to other sourc e categories. The recommended performance specifications provide the basis for determining the initial acceptability of the CEMS and th e quality assurance requirements provide a basis for determining the ongoin g acceptability of data and monitoring equipment. Th e qualityassurance recommendations include criteria for decidin g tha t a monitoring system is "out-of-control" and state that dat a collec ted during such periods cannot be used to satisfy minimu m data capture (i.e., data availability) requirements. A minimu m da ta availability requirement has been included in the qualit y assurance recommendations. It is recognized that some states may

re quire higher levels of CEMS availability, or define CEM S availability in other terms. The additional requirements associated with the workgrou p recommendations will increase the costs of CEMS performance tests and quality assurance activities. However, for many sources th e additi onal cost will be relatively small since effective CE M programs which can meet the recommended requirements have already beendeveloped and implemented. It is hoped that the guideline s will help avoid costly misunderstandings between the source and the
age ncywhich can result in the purchase or installation o f unacceptable equipment. The i ncremental costs attributable to the NESCAUM workgroup recommendations are believed to be a relatively small fraction of the total costs for MWC facilities.

1. Su mmary of Performance Specification Recommendations for Ga s CEMS NE SCAUMworkgroup recommendations for performanc e specifications for SO2 and NOx CEMS, CO CEMS, and HCl CEMS ar e pre sented in Section 2 through 4 of this document, respectively

. The recommendations reference the federal regulations. Majo r differences include: a. Calibration gases are required to be used for daily cali bration ch ecks, performance tests and periodic audits of all CEMS

. Ca librationof the entire measurement system is required

. Procedures are included to allow source owners or operators t o demonstrate alternate procedures and alternate methods fo r calibration checks and audits. These requirements are designed to eliminate use of calibration procedures that check only a portion of the measurement system and procedures that have not bee n evaluated and documented by the user. b. The values of calibration gases used for drift tests and daily calibr ationchecks must be determined quantitatively. Severa l
pro cedures are provided to establish the values of the gases

. These requirements are necessary to assess the accuracy of th e monitoring data on a daily basis. c. A four-point linearity test must be performed for gas mo nitors.This can be done with the two gases used for the daily checks and

two Protocol 1 gases used for quarterly audits. (A three-poin t check is required for HCl monitors.) This requirement is ne cessary to eliminate the use of non-li near monitoring systems which may be adjust edto provide the correct response at zero and upscal e calibr ationcheck points but do not necessarily provide accurat e data at other concentrations. d. An additional minimum accuracy specification e.g., mea n differe nce not to exceed 5 ppm, or equivalent (10 ppm for C O

mo nitors) is added to prevent the accuracy specifications fro m being overly restrictive for those applications where emissio n levels are very low. The relative accuracy test procedures ar e also clarified to eliminate some of problems that are encountered in conducting these tests at MWC facilities. e. A cycle time/response time specification and test procedure is added for all monitors. The s pecification for SO2 , NOx, diluent, and H Cl monitors is 15 minutes which is consistent with the EP A requir ements in 40 CFR 60.13. A one-minute cycle time/respons e tim e specification is included for CO monitors since some state s will require reporting of one-minute values for this pollutant. 2. Summary of Quality Assurance Recommendations for Gas CEMS NESCAUMworkgroup recommendations for quality assuranc e requirem ents for all gas CEMS are presented in Section 5 of thi s document. The recommendations reference the federal regulations

. Major differences include:

a. Subm ission of a preliminary monitoring plan to the agency i s require din most cases. The plan should set forth the basi c approachthat will be used to comply with the monitorin g requirements. It is hoped that agency review of the plan wi ll help resolve misunderstandings, unacceptable approaches, and confusion about the monitoring requirements before costly mistakes occur. b. A CEMS quality assurance plan should be developed for eac h facility. Detailed guidance is provided with respect to the Q A plan content.

c. An annual review of the QA plan and results of it s implementation is required to be performed by the source owner or operat or. The results of this review and changes to the QA pla n are reported to the agency. d. Routine zero and upscale calibration checks of the monitoring syste mmust be performed on a daily basis. This requirement i s equivalent to the daily calibration check in 40 CFR 60.13 excep t that the procedures recommended here are similar to those de scribed for the performance specification test.

e. A cylinder gas audit consisting of the four-point linearit y test described in the performance specification recommendation s should be performed each calendar quarter. Only routin e calibration adjustments accord ing to the written procedures in the QA plan are permitted before the audit. f. A re lative accuracy test should be performed in one calenda r quarter immediately before or after the cylinder gas audit. Th eCEM S must pass both tests for performance to be considere d

acceptable.
g. A minimum data availability specification of 90 percent o f source operating hours is included. The time required for z ero and
upsc ale calibration checks, cylinder gas audits, and certain Q A activities included in approved plans is not subtracted from CEMS availability. 3. Summary of Performance Specification Recommendations fo r Opacity CEMS
NE SCAUMworkgroup recommendations for performanc e specifications for opacity CEMS are presented in Section 6 of this document. The recommendations reference the federal regulations

. Major differences include: a. All opacity monitors must provide external calibration filter access to facilitate performance audits. b. All opacity monitors must provide access to instantaneous o r one-minute opacity measurements in addition to six-minute av erages.
c. Calibration error tests must be performed in the field or a perfor mance audit must be conducted to demonstrate that tes t results from the manufacturer are representative of performance of the installed monitor. 4. Summary of Quality Assurance Recommendations for Opacity CEMS NESCAUMworkgroup recommendations for quality assuranc e requirements for opacity CEMS are presented in Section 7 of thi s document. The recommendations are similar to the requirements for gas CEMS except: a. A opacity monitor performance audit is conducted insteadof the cylinder gas audit that is required for gas monitors. b. A zero alignment procedure is performed for opacity monitor s insteadof the relative accuracy test that is required for ga s CEMS.SECTION 2

PERFORMANCE SPECIFICATIONS FOR SO2 AND NOx CEMS AT MUNICIPAL WASTE COMBUSTION FACILITIES

This section describes the NESCAUM workgroup recommendations for monitor location requirements, equipment and performanc e specifications, and corresponding test procedures for SO2 and NOx CEMS i nstalled at MWC facilities. Specifically, the NESCAU M workgroup recommends that states consider adopting the EP A requirements contained in "PERFORMANCE SPECIFICATION 2

- SPECIF ICATIONAND TEST PROCEDURES FOR SO2 AND NOx CONTINUOU S EMI SSIONMONITORING SYSTEMS IN STATIONARY SOURCES" of 40 CFR 60
, Appendix B revised as of July 1, 1988, with the changes deta iled in Items 1 through 8 below. When emission standards necessitate use of a diluent monitor (O2 or CO2) to determine emissions in u nits of the standard, NESCAUM recommen ds that states consider adopting the
EPArequirements contained in "PERFORMANCE SPECIFICATION 3

- SPECIF ICATIONS AND TEST PROCEDURES FOR O2 AND CO2 CONTINUOU S EMI SSIONMONITORING SYSTEMS IN STATIONARY SOURCES" of 40 CFR 60
, Appendix B revised as of July 1, 1988, with the changes detaile d below.

1. Use of Calibration Gases
Ad esign specification should be added to require that SO2
, NOxand diluent monitors be able to accept calibration gases fo r dailycalibration checks, performance specification tests, an d perio dic quality assurance audits. Furthermore, the desig n spec ificationshould require that the calibration gas injectio n point be in the sample probe or at the probe outlet so that th e enti re measurement system is checked when calibration gases ar e introduced to the monitoring system. For measurement system s employing dilution probes or similar devices, the calibratio n gases must be introduced prior to the dilution point and in such amanner that they are diluted to the same extent as the sample gases from the effluent stream. Similarly, for sample acquisition system s usin g aspirators or eductors, the calibration gases must b e introduced prior to these devices even if these components a re part of the sample probe assembly. Sourc e owners or operators (or instrument vendors) ma y de monstrate that alternate daily calibration check procedures o r devices provide results comparable to those obtained by usin g calibrationgases to check the entire measurement system. Fo r example, a source owner or operator may elect to demonstrate th e validi tyof an alternate calibration check procedure for (1 ) in-situ monitors that accept calibration gases and which also use calibration gas cells, or (2) for extractive monitors where daily

ca librationchecks of the entire system are unnecessaril y burdensome. In such cases, a demonstration can be accomplished by

con ducting concurrent calibration drift tests using both th especif ied method and the alternate method during the performanc e

spec ificationtest. If the results indicate acceptable monito r pe rformance with respect to the applicable drift specifications
, the alternate procedure may be used for the daily zero and upscale checks of the monitor. However, the quality assurance plan mus t incl ude (1) a detailed discussion of all assumptions associate d with t he alternate procedure, and (2) mandatory procedures fo r conduc ting periodic comparisons of the specified and alternat e calibr ationmethods. Such comparisons should be performed on a
mon thlyor more frequent basis until the alternate procedure ha s been evaluated and documented to the satisfaction of the agency. Source owners or operators may request approval of alternate routine calibration check procedures for monitors that canno t

ac cept calibration gases and alternate procedures for conductin g the linearity and response time tests for these monitors. Source

own ers or operators are cautioned that alternate calibratio n procedures need to be evaluated carefully and thoroughly and that a single relative accuracy test at one operating condition d oes not provid e a sufficient evaluation of the validity of a particula r calibration procedure. The so urce owner or operator should submit a written plan to the agency for conducting such a demonstration. If the plan is approved, the source owner or operator may ca rry out the demonstration program and submit a detailed report describing the alternate procedure, all assumptions associated with th e al ternate procedure, the procedures and conditions of th e demonstration, the results of the tests conducted, and appropriate revisions to the CEMS quality assurance plan, as applicable. The vali dityof any alternate procedure would be re-examined durin g quarterly accuracy audits.

2. Data Availability and Back-Up Data Recording Devices All CEMS must operate continuously without repairs
, unscheduledmaintenance, or non-routine adjustments during th e performance specification tests to determine calibration drift
, linear ity, and relative accuracy. In addition, minimum dat a availability specifications are included as QA requirements and are applicable to the operation of the CEMS after completion of th e performance specification tests. (See Section 5, Quality As surance Requiremen ts for SO2, NOx, CO, and HCL CEMS, 8. Minimum Dat a Availability Requirements of this document.) Mos t CEMS at MWC facilities will include a computer dat a acquisition system that performs various operations including (1) recording effluent concentrati on measurements, (2) recording daily cali brationcheck results, (3) compensation of effluen t

mea surements for drift, (4) calculation of emissions in units o f the standard, (5) averaging of measurement data, (6) generatin g excess emission reports, and (7) interfacing with telecommun ication systems where required by the agency. Data acquisition syst ems are inherently monitor- and source-specific and may need to acco mmodate di verse reporting requirements of various states, therefore muc hflexi bilityin the design of these systems is needed. When th e

data acquisition system is inoperative, many vital CEMS functions

are suspended and data availability is immediately affected

. Sou rce owners and operators are encouraged, but not required, t o include a back-up recording de vice or other appropriate redundancy within the data acquisition system to maximize data availability. Where such devices are used, conformance with the calibratio n drift and linearity specifications s hould be determined based on results obtainedfrom both the primary data acquisition system and th e back-up recording devices in order to avoid additional testi ng when the back-up recording device is placed in service. However
, failure of a performance specification based on data from a back-up recording device should not necessitate retesting.

3. Calibration Drift Test and Reference Values The calibration drift specific ations for SO2 and NOx monitors (2.5 p ercent of span) and O2 and CO2 monitors (0.5 percent O2 o r CO2) as well as the calibration drift test procedures i n Performance Specifications 2 and 3 should be maintained exce pt that (1) the calibration drift tests must be performed using cali bration gases or other prior approved alternate calibration procedure, and (2) the concentration value of the calibration gases must be known. The values of the calibration gases may be established through the

use of certified reference materials (CRMS), standard referenc e
ma terials (SRMS), or EPA Protocol 1 gases. Alternatively
, calib rationgas values determined by the gas manufacturer' s certified analysis (i.e., + 2 % of tag value) may be used if the concentrationis checked by direct comparison with Protocol 1
gases, or by triplicate analysis using an appropriate EPA tes t methodor an equivalent procedure. The direct comparison of ta g values and Protocol 1 gases can be accomplished using the in stalled CEMS in most cases. Compar isonwith Protocol 1 gases may be accomplished by introducing both the subject gas, a zero concentration gas and at least two Protocol 1 gases into an analyzer demonstrated pre viously to meet the linearity test specification in Item 4, below

. (Ambient air and two Protocol 1 gases may be used for O2 monitors whichcannot analyze zero gas.) The Protocol 1 gases shoul d satisfy the audit range specif ications of Appendix F, Procedure 1; however, alternate ranges including at least two Protocol 1 gases which bracket the concentration value of the subject gas may also be used, subject to the approval of the agency. The analyze r responses to all of the Protoc ol 1 calibration gases shall be used to construct a calibration curve for the analyzer. The analyze r response to the subject gas and the calibration curve shall be used to determine the concentration of the subject gas. If th e difference between the measure d concentration and the tag value of the subject gas is less than 3 percent of the tag value, use th e tag value as the actual concentration. If the difference between the measured concentration and the tag value is greater than 3percent of the tag value, repeat all gas injections and check all

calculations. If the difference still exceeds 3 = percent of the tag value, use the measured concen tration as the actual concentration. (See 40 CFR 60, Appendix A, Method 6C, "6.1.2 Alternative Number 2" for specific requirements for the analysis of SO2 calibratio n gases by EPA test methods. Similar procedures may be used for th e
an alysis of NO and diluent calibration gases. See Method 7E
, Section 6.1 for analysis criteria for NO calibration gases.) Calibration drift tests are intended to identify problems th at af fect the stability of the monitor calibration; however, suc h tests are conducted over a short period and therefore canno t represent the full range of operating conditions for the CEMS

. Experience has shown that many of the problems resulting i n excessive calibration drift and loss of monitoring data are related to poorly conditioned electrical power, inadequate or unsuitabl e compressed air supply, excessive vibration, ambient temperatur e changes, ambient dust loading, and other site-specific application problems. Source owners and operators are strongly encouraged to identify these and other probl ems that may affect CEMS performance and take appropriate actions t o minimize the loss of CEMS data due to these problems.

4. Linearity Test A new performance specification and test procedure should be added to require a four-point cylinder gas audit to demonstr ate the lin earityof each pollutant and diluent monitoring channel. Th e linear ityspecification and test procedure applies to the entir e monitoring channel, including the data acquisition system, a s installed and operated at the MWC facility. (A non-linear a nalyzer used i n conjunction with appropriate adjustments by the dat a acquisition system is acceptable.) Source owners and operat ors are encouraged, but not required, to have equipment vendors demo nstrate conformance with the linearity specification prior to shipment of the CEMS to the subject facility. However, the linearity test is required to be conducted for each CEMS after installation. The linearity test should use the zero and upscal e cal ibrationvalues used for the daily calibration checks and th e two audit points specified for cylinder gas audits by Appendix F, Procedure 1. If the high range audit point (i.e., 50 to 60 percent of the pollutant monitor span) of Procedure 1 is used for th e daily upscale checks, an audit gas o f 80 to 90 percent of span should be substituted for the high range audit point. Protocol 1 gase s, CRMS or SRMS should be used for the two audit points that supplem ent the dailycalibration checks. Three non-consecutive measurement s should be made for each of the calibration gases (e.g., zero, low, mid, high, zero, low, mid, high, etc.) The linearity specification should require that the mea n differ ence between the calibration gas value and the monito r responses at each of the four points be calculated from the three measurements. The mean differ ence at all four test points must beles s than 5 percent of span for SO2 and NOx monitors and 0. 5

percent O2 or CO2 for diluent monitors. The linearity test should be performed as soon as practica l before or after the relative accuracy test. Only the routin e calibr ationdrift adjustments are allowed between the two tests

. Othe r adjustments or repairs to the monitoring system woul d necessitate repeating the linearity and the accuracy test. (During subsequent quarterly audits, only calibration drift adjustment s according to the written procedure contained in an approved QA plan

are allowed prior to the linearity test or the relative accurac y test.)

5. Relative Accuracy Test The workgroup recommends that states maintain the performance
spec ificationtest procedures for the relative accuracy test i n Performance Specification 2 with the clarifications describe d below. The daily calibration checks should be performed on eac h daythat the relative accuracy testing is performed and that n o adjustments or repairs to the monitoring system other than th e routin e calibration drift adjustments may be conducted. Th e distinction between routine adjustments and corrective action for

a ma lfunctioning CEMS is particularly difficult for the initia l relative accuracy test since t here is little or no track record on whichto base decisions and since the QA plan is usuall y incomplete. The following app roach is recommended to resolve this issue. Prior to conducting the test, the source operator mus t establ ish(1) the criteria for adjustment of the monito r cal ibration, (2) the criteria or schedule for the performance o f routine maintenance activities, and (3) the frequency or criteria for conducting additional calibration checks. This informatio n shouldbe made available to the agency observer. The dail y calib rationchecks should be performed following the norma l procedure before initiating the test and adjustments should only be made as indicated by the applicable criteria. During the te st, the source may check the calibrati on at reasonable intervals and abort the te st if unscheduled maintenance or adjustment are necessary

. If corrective action other than routine adjustments are required,

a 24- hour period should elapse to verify that the CEMS drift i s within acceptable limits befor e a new test is begun. The new test may begin immediately, subject to the approval of the agency , if it

canbe shown that the corrective action or adjustment does no t affect the calibration drift of the CEMS. Performance Specifications 2 and 3 require only that th e
re lative accuracy test be performed for the entire measuremen t system(i.e., pollutant and diluent monitor) in units of th e applicable standard. However, the source owner or operator i s strong lyencouraged, but not required, to determine also th e relative accuracy for each monitoring channel in units o f concentrationin order to obtain a more complete evaluation o f monitor performance.Pr oblems in conducting the relative accuracy tests may b e

encountered where significant fluctuations in the emission levels

or very low emission levels are encountered. Therefore, bot h relative accuracy specifications in Performance Specification 2 (i.e., relative accuracy less than 20 percent of the mean re ference value or less than 10 percent of the standard) should be retained. Also, an additional specification should be added to provide a n absolu te minimum accuracy specification of 5 ppm mean differenc e for SO2 or NOx CEMS relative to the test method. (See Appendix A for a technical discussion of the various accuracy specifica tions.) Thus, for a concentration standard corrected to 7 percent O2 th e following accuracy specifications should apply; relative accuracy less than 20 percent of the mean reference value, relative a ccuracy less than 10 percent of the st andard, or mean difference less than 5 ppm corrected to 7 percent O2, whichever is least restrictive

. For cases where the emission standard is expressed in units o f lb/M M = Btu, an equivalent absolute accuracy specification may b e calculated using an average or typical diluent concentration. For

ex ample, it can be shown that 5 ppm SO2 at 7 percent O2 i s approximately equivalent to 0.01 lb/MM = Btu using the F-Fact ors and conversion values in EPA Method 19. For sources subject to an SO2 or NOx percent removal standard that is more restrictive than the emission standard (or wher e there is n o absolute emission standard) an implicit emission standar d should be determined as: Impl icit Standard = [1-Percent Removal/100] x Avg. Uncontrolle d Emissions The implicit emission standard should be used to calculate th e relative accuracy result as "10 percent of the standard." F or this det ermination, the uncontrolled emissions may be obtained by averaging all of the reference test data from the relative a ccuracy test of the CEMS at the inlet to the control device. The relative accuracy test procedures should be clarified to

ex plicitlyprohibit modification of the operation of time-share d CEMS during the test to increase the sampling frequency, t o min imize the frequency of sample system cleaning (blow-back ) operations or, to reduce the number of locations from which CEM S samples are obtained. In order to minimize the effects o f fluctuating emission levels, the source owner or operator ma y choose (1) to extend the sampling time to at least 1 hour fo r int egrated sampling methods, or (2) to increase the number o f samples that are obtained during a run for grab sampling methods. Al ternate relative accuracy test procedures for time-shared CEM S that reduce the number of locations for which reference samp les are obtained may be approved by the agency on a case-by-case basis. The source owner or operator may use EPA Method 6 o r in strumental Method 6C for SO2 concentration measurements fo r relative accuracy tests. Meth ods 7, 7A, 7C, or 7D or instrumental Met hod7E may be used for NOx concentration measurements, an d Method 3 or = instrumental Method 3A may be used for O2 or CO 2concentrationconcentration measurements for relative accurac y

tests. NOTE: Methods 7C and 7D may be subject to analytica l interferences when used at MWC sources; the applicability of these methods has not been established by field testing at this time.

6. Alternate Accuracy Test Procedure Section10. Alternative Procedures of Performanc e Specification 2 contains procedures for conducting a cylinder gas audit in place of a relative accuracy test when a waiver of th e relative accuracy test require ment is granted under the conditions specified in 60.13 (j). According to these regulations, a source

owner or operator may petition the Administrator for a waiver o f the relative accuracy test requirement when the CEMS is not th e compliance method and when the emissions are less than 50 = percent of the s tandard as determined by a source performance test. Th e regu lations specify the content of the petition, the condition s wh enit may be applied for, and the conditions under which th e waiver may be rescinded. The Performance Specification 2 cylinder gas audit procedures

are not needed because the same audit test points are alread y included as part of the more elaborate linearity test that i s recommended for all CEMS insta lled at MWC facilities. (See Item 4 above.) As with any requirement, the agency may waive the r elative

acc uracytest requirement in cases where the emission levels ar e very low as indicated by the results of source performance t ests or other independent effluent measurements regardless of whether the CEMS are used as the compliance method. However, no genera l guidance or criteria is provided here for waiving the relativ e accuracy test requirement.

7. Cycle Time and Response Time Test
As pecification should be added that requires all SO2, NOx
, anddiluent CEMS to complete at least one cycle of operatio n (sampling, analyzing, and data recording) for each successiv e 15- minute period, (i.e., a minimum of four samples per hour)

. Ext ractive monitoring systems may be time-shared between tw o measurement locations; however , the cycle time requirement must be met for both measurement locations. (Some states have adopte d regulations or policies prohibiting any time-sharing of moni tors at MWC facilities, and some state s will allow time-sharing only as an emergency backup provision.) Source owners and operators are encouraged to instal l monitoring systems fully capable of representing emissions f rom the facility. The agency should not excuse apparent excess emissions that may be due to nonrepresen tative sampling because of long CEMS cycle times or minimum CEMS sampling frequencies. In addition
, sources required to install and operate NOx control equipment may be subject to shorter measurem ent cycle time specifications in the future.Are sponse time test should be added to determine if eac h

mo nitoring channel of the CEMS complies with the cycl e time /sampling frequency specification. The average upscale an d down scale response times should be determined from thre e repetiti ons of each test. The greater of the average upscale o r average downscale response times should be reported as the r esponse time for the system. The upscale response time should be determined by injecting zero gas into the measurement system and then recording the amount of time required for the system to return to the effluen t

concen trationafter the zero gas injection has been stopped

. Si milarly, the downscale response time should be determined by inj ecting a high range calibration gas and then recording th e amount of time required for th e monitoring system to return to the effluent concentration after the gas injection is stopped

. Specifically, the response time may be measured as the tim e requir edfor the monitor to complete 95 percent of th e
concen trationstep-change occurring after the gas injection i s stoppedduring each test. For monitoring systems that perform a series of operations, (purge-b low back, sample, analyze, etc.) the inj ectionof calibration gases should be timed to produce th e longest response time.
In man y cases, the actual response time of the measuremen t sy stemis only a few seconds as compared to several minutes t o perform the necessary cycle of operations. In these cases, it is ofte npossible to establish conformance with the cycle tim e requirement by inspection of the system rather than by injec tion of calibration gases. Such determinations are subject to the a pproval of the agency.

8. Data Reporting Equipment Specifications Additional equipment or designspecifications may be added by st ates to facilitate the specific record keeping and reportin g requirements that may apply. Various state agencies are currently considering a wide range of alternatives including: automat ed data reporting using magnetic media, telecommunication systems tha t allo wagency representatives to obtain or review data on-deman d fromr emote locations, and real-time or intermittent telemetr y systems for CEM data and information. No additional guidance i s incl uded because of the diversity of state requirements an d approaches.SECTION 3

PERFORMANCE SPECIFICATIONS FOR CARBON MONOXIDE CEMS AT MUNICIPAL WASTE COMBUSTION FACILITIES

This section describes the NESCAUM workgroup recommendations for monitor location requirements, equipment and performanc e specifications, and corresponding test procedures for CO CEM S installed at MWC facilities. Specifically, the NESCAUM workgroup recommends that states consider adopting the EPA requirement s contained in "PERFORMANCE SPEC IFICATION 4 - SPECIFICATION AND TEST PROCEDURES FOR CARBON MONOXIDE CONTINUOUS EMISSION MONITORIN G SYSTEMS IN STATIONARY SOURCES" of 40 CFR 60, Appendix B revised as of July 1, 1988, the Federal Register Vol. 53, No. 204, October 21,1988, and the changes detailed in Items 1 through 8 below. Many of the changes that are recommended for CO monitors are the sa me as those recommended for SO2 and NOx CEMS. For th e purposes of these discussions it is assumed that the CO monitor is

use dto measure emission levels in units of concentration (ppm)

. Where a diluent monitor is use d to adjust the data to a consistent basis (e.g., 7 percent O2 or 12 percent CO2) or where data i s to be reported in terms of combustion efficiency, appropriate adju stments to the recommended requirements should be made. It is assum ed that the upper limit of the CO measurement range (span value) would be approximately 300 to 500 ppm. Greater measurement ranges may be neededfor facilities using refuse-derived-fuels particularl y during start-up. Alternate me asurement ranges may be used subject to the approval of the agency when emission levels are consi stently much lower than the standard.

1. Use of Calibration Gases
Adesign specification should be added to require that C O monitors be able to accept cal ibration gases for daily calibration checks, performance specification tests, and periodic qualit y assurance audits. In addition, the recommendations regardin g where the gases are introduced to the measurement system, the appl ication to dilution sampling systems, and the requirements fo r demonstrating the adequacy of alternate calibration techniques are the same as described in Section 2 for SO2 CEMS. Special considerations may app ly to CO monitors which utilize a correction procedure to eliminate the influence of CO2. It may be necessary to use CO calibration gases with a specifi c
conc entrationof CO2 to assess monitor performance. Additiona l monitor-specific procedures wo uld be needed to verify the accuracy of the correction procedure. These procedures should be evaluated and approved by the agency on a case-by-case basis.

2. Data Availability and Back-Up Data Recording Devices All CEMS must operate continuously without repairs
, unscheduledmaintenance, or non-routine adjustments during th eperformance specification tests to determine calibration drift
,

linear ity, and relative accuracy. In addition, minimum dat a availability specifications are included as QA requirements and are applicable to the operation of the CEMS after completion of th e performance specification tests. (See Section 5, Quality As surance Requir ements for SO2, NOx, CO, and HCL CEMS, 8. Minimum Dat a Availability Requirements.) Recommendations and suggestions regarding the use an d
per formance testing of back-up recording devices for CO CEMS ar e the same as described in Section 2 for SO2 CEMS.

3. Calibration Drift Test and Reference Values
Inmany cases, the daily upscale calibration check valu e required by Performance Specif ication 4 (i.e., 50 to 90 percent of span) is very much greater tha n both the normal CO operating level andthe level of the emission standard. Calibration checks a t these levels may not represent actual performance of the monitor. The requ irement should be revised to allow the use of an upscal e cali brationcheck value that either (a) approximates the C O concentration equivalent to the applicable emission limit, or (b) is wit hin 50 to 90 percent of the span value. Other upscal e calibration check values may be used subject to the approval of the agency. Source operators may elect to conduct additional ch ecks of the CO monitor calibration to evaluate the monitoring data fo r their own uses. The c alibration drift specification for CO monitors i n Performance Specification 4 (d rift not to exceed 5 percent of span for 6 out of 7 test days) should be changed to restrict drift to 3 per cent of span for 7 consecutive days. The more restrictiv e li mit is consistent with the capabilities of contemporar y instrumentation. Also, the expression of the limit not to b e exceeded for 7 consecutive days is necessary for the impleme ntation of Appendix F, Procedure 1 control limits. The drift test procedures in Performance Specification 4 sho uldbe maintained except that (1) the calibration drift test s must be performed using calibration gases or other prior approved alternate calibration procedure, and (2) the concentration v alue of the ca libration gases must be known. The specifications an d procedures that may be used for establishing the values of th e calibrat iongases are the same as described in Section 2 for SO 2 CEMS. The suggestion that the source owner or operator identify application problems that may affect the stability of the CO CEMS is also the same as for SO2 CEMS.

4. Linearity Test A new performance specification and test procedure should be added to require a four-point cylinder gas audit to demonstr ate the linear ityof CO monitors. The linearity specification and tes t proced ures apply to the entire monitoring channel, including th e dat a acquisition system, as installed and operated at the MW Cfa cility. (A non-linear analyzer used in conjunction wit h

ap propriate adjustments by the data acquisition system i s acceptable.) Source owners and operators are encouraged, but not

re quired, to have equipment vendors demonstrate conformance wit h the linearity specification prior to shipment of the CEMS to th e facility. However, the linear ity test is required to be conducted for each CEMS after installation. The requirements for the selection of the audit points fo r the linearity test and the tes t procedures for CO monitors are the

same as described in Section 2 for SO2 CEMS. The linearit y specification should require that the mean difference between the calibration gas value and the monitor responses at each of t he four points be calculated from the three measurements. The mea n difference at all four test points must be less than 5 percent of span for CO monitors. The linearity test should be performed as soon as practica l before or after the relative accuracy test. Only the routin e calibr ationdrift adjustments are allowed between the two tests

. Othe r adjustments or repairs to the monitoring system woul d necessitate repeating the linearity and the accuracy test. (During subsequent quarterly audits, only calibration drift adjustment s according to the written procedure contained in an approved QA plan

are allowed prior to the linearity test or the relative accurac y test.)

5. Relative Accuracy Test The recommended procedures and conditions for the relativ e accuracy test are the same as those described above for SO2 CEMS.
In add ition, the workgroup recommends that both of the relativ e accuracyspecifications in Performance Specification 4 (i.e.
, relative accuracy less than 10 percent of the mean reference value

or les s than 5 percent of the standard) be retained. Also, a n addi tional specification should be added to provide an absolut e minimu maccuracy specification of 10 ppm mean difference for C O CEMS relative to the reference test method. Thus, for a concentration standard the following accuracy specifications should
app ly: relative accuracy less than 10 = percent of the mea n ref erence value, relative accuracy less than 5 percent of th e standard, or mean difference less than 10 ppm, whichever is least restrictive. Where necessary, the 10 ppm mean difference li mit may be converted to an equivalent limit expressed in units of th e applicable standard using the average diluent concentratio n
me asured during the relative accuracy test and applicabl e conversion factors.

The re lative accuracy test should be performed using Metho d 10. When the installed CEMS uses a nondispersive infrared (NDIR)

ana lyzer, Method 10 shall use the alternative interference tra p specified in section 10.1 of the method. Method 10B is a n accept able alternative to Method 10. The following alternative smay be approved by the agency in specific cases.

Alternative 1 - The test may be conducted using Method 10 without th e interference trap if a laboratory interference test i s performed for the analyzer prior to the field test. The lab oratory interference test should include the analysis of SO2, NO, and CO2 calibration gases representing the range of expected effluen t

co ncentrations. Acceptable performance is indicated if the C O analyz er response to each of the gases is less than 1 percent o f the applicable measurement range of the analyzer.

Alternative 2 - The test may be conducted using Method 10 without

aninterference trap, and without a CO2 trap, subject to th e approval of the agency, based on the submission of informatio n de monstrating the absence of CO2 interference for the tes t analyzer. (If this option is chosen, any interferences that ar e present will cause the test analyzer to be biased high. There is also a possibility that the installed monitor would be subject to the sa me interference which would not be detected during th e relat ive accuracy test. The potential for the high bias may b e acceptable to the agency provided that the source owner or o perator accepts the potential bias andcannot later challenge the accuracy of the data.)

6. Alternate Accuracy Test Procedure As described in Section 2 for SO2 CEMS, the alternate accura cy test procedure for CO monitor are not needed since the mor e elaborate linearity test is re quired for all CO monitors installed at MWC facilities. The agency may waive the relative accura cy test requirement if the emissions a re consistently very low (e.g., less than 2 0 ppm) based on source performance test results (i.e.
, "compliance tests") or other independent effluent measurements

. The agency should be cautious in waiving the relative accura cy test requir ement based solely on CEMS data since some analyzers hav e been found to respond poorly to low concentrations of CO.

7. Cycle Time and Response Time Test For sources subject to an emission limit with a one-hour o r shor ter averaging period, an additional specification should b e included that requires the CO CEMS to complete at least one cycle of operation (sampling, analyzing, and data recording) for each successive one-minute period, (i.e., 60 samples per hour) with an allowance of 10 = minutes per hour for cle aning and calibration operations. For sources subject t o limits with longer averaging periods, alternate cycle tim e specifications may be established by the agency. A response time test should be added to determine if the CO monitor meets th e cycle time/s ampling frequency specification. The response time tes t should be conducted according to the procedures described ab ove forSO2 CEMS.

CO monitors with response times exceeding the applicable cyc le tim e specification are acceptable if the longer response time i s due to delay or "lag" time at tributable to the sample acquisition
equ ipment. For these monitors, performance is acceptable if th e time between the analyzer's initial response and the respons e equivalent to 95 percent of the actual concentration change is less than the cycle time specificat ion (regardless of the delay between the analyzer's initial response and the time that the gas in jection is stopped during the response time test) provided that the total response time does not exceed 15 minutes.

8. Data Reporting Equipment Specifications Additional equipment or designspecifications may be added by st ates to facilitate the specific record keeping and reportin g requirements that may apply. Various state agencies are currently considering a wide range of al ternatives including: automated data reporting using magnetic media, telecommunication systems tha t allo wagency representatives to obtain or review data on-deman d fromr emote locations, and real-time or intermittent telemetr y systems for CEM data and information. No additional guidance i s incl uded because of the diversity of state requirements an d approaches.SECTION 4

PERFORMANCE SPECIFICATIONS FOR HCl CEMS AT MUNICIPAL WASTE COMBUSTION FACILITIES

Some states may require that HCl CEMS be used to monito r emis sions and/or determine HCl control efficiency at MW C facilities. The NESCAUM workgroup did not address nor attempt to determine whether HCl CEMS should be installed at MWC facilities. It is noted that the EPA has not adopted performance specifi cations for HCl monitors in Part 60 an d has not announced plans to require HCl monitors at MWC facilities or any other sources regulate d under the New Source Performance Sta ndards. Nevertheless, the NESCAUM workgroup recommends appropriate monitor location requirements
, equipment and performance specifications, and corresponding tes t procedures for HCl CEMS instal led at MWC facilities. This section des cribes the NESCAUM workgroup recommendations for HCl CEM S performance specifications based on currently availabl e information. Changes to these specifications may be appropr iate as additional information and ope rational experience with HCl CEMS is obtained. For the purposes of these discussions it is assumed tha t Performance Specification 2 would serve as a basic model for HC l requirements. Also, many of the changes that are recommende d above for SO2 and NOx CEMS are also appropriate for HCl CEMS. It i s assumed that HCl monitors woul d be used to measure emission levels in units of concentration (ppm). Where a diluent monitor is used to adjust the data to a consistent basis (e.g., lb/MM = Btu, 7 per cent O2, or 12 percent CO2) appropriate adjustments to th e recommendedrequirements should be made. It is assumed that th e HCl me asurement range for controlled emissions would b e approx imately250 ppm and that the measurement range fo r uncontrolled emissions would be approximately 1500 = ppm.

1. Use of Calibration Gases
Adesi gn specification should be added to require that HC L monitors be able to accept cal ibration gases for daily calibration checks, performance specification tests, and periodic qualit y assurance audits. In addition, the recommendations regardin g where the gases are introduced to the measurement system, the appl ication to dilution sampling systems, and the requirements fo r demonstrating the adequacy of alternate calibration techniques are the sa me as described above for SO2 CEMS. Because of the highe r cost for HCl calibration gases and the amount of gas used by some of the currently available monitors, it is expected that a dem onstrationof an alternate calibration technique would b e attempted for most HCL CEMS applications.

2. Data Availability and Back-Up Data Recording DevicesAll CEMS must operate continuously without repairs
,

unscheduledmaintenance, or non-routine adjustments during th e performance specification tests to determine calibration drift
, linear ity, and relative accuracy. In addition, minimum dat a availability specifications are included as QA requirements and are applicable to the operation of the CEMS after completion of th e performance specification tests. (See Section 5, Quality As surance Requir ements for SO2, NOx, CO, and HCL CEMS, 8. Minimum Dat a Availability Requirements of this document.) Recommendations and suggestions regarding the use an d performance testing of back-up recording devices for HCl CEMS are the same as described in Section 2 for SO2 CEMS.

3. Calibration Drift Test and Reference Values A calibration drift specification for HCl monitors restricti ng drif t to 5 percent of span for 7 consecutive days should b e established. The drift test procedures in Performanc e Specification2 should be used except that (1) the calibratio n drift tests must be performed using calibration gases or othe r prior approved alternate calibration procedure, and (2) the value of the calibration gases must be obtained from the vendor s certified analysis (within three months of the performance t est) or by performing triplicate analysis of the gases using proposed EPA Method 26. The suggestion that the source owner or operato r identify application problems that may affect the stability of the monitor is also the same as for SO2 CEMS.

4. Linearity Test A performance specification and test procedure should be add ed to require a three-point cylinder gas audit to demonstrate th e linear ityof each HCl monitor. The linearity specification an d test p rocedure apply to the entire monitoring channel, includin g the data acquisition system, as installed and operated at th e partic ular facility. (A non-linear analyzer used in conjunctio n wi thappropriate adjustments by the data acquisition system i s acceptable.) This test should use the zero and upscale cali bration gas used for the daily calibration checks and an additional audit point at 20 to 30 percent of s pan. The recommended procedures for performi ng the test are the same as described above for SO2 CEM S except that Protocol 1 gases are not available for HCl. The refore, the concentration value of all three calibration gases should b e det ermined as described above in Item 3. The linearit y specification should require that the mean difference between the calibrationgas value and the monitor responses at each of th e three points be calculated from the three measurements. The mean difference at all three test p oints must be less than 5 percent of span for HCl monitors.

5. Relative Accuracy Test The recommended procedures and conditions for the relativ eaccuracy test are the same as those described above for SO2 CEMS.

The following accuracy specifications are also recommended : relative accuracy less than 20 percent of the mean reference value, relative accuracy less than 10 percent of the standard, or mea n difference less than 5 ppm, whichever is least restrictive. For

cases where the emission standard is expressed in units of lb/M M Btu or corrected to a specified O2 or CO2 concentration, a n absolute accuracy specification equivalent to 5 ppm should b e calcul ated using an average or typical diluent concentration an d applicable conversion factors. The appropriate procedures for use in cases where a percent remov al standard is more restrictive than the emission standard are the same as for SO2 CEMS. The relative accuracy test should be performed using proposed EPA Method = 26. 6. Alternate Accuracy Test Procedure The same considerations apply to the alternate accuracy test procedure for HCl monitors as were described above for SO2 CEMS.
In ess ence, the alternate accuracy test procedure is not neede d since the more elaborate linearity test is required for all HC l CEMS installed at MWC facilities. The agency may decide to waive the relative accuracy test requirement if the emissions ar e consistentlyvery low as indicated by source performance tes t

re sults (i.e., "compliance tests") or other independent effluen t

mea surements. However, the relative accuracy test should not b e waived based on low concentrations indicated by the HCl CEM S because of the possibility of significant or total loss of HCl in the effluent samples within the sample acquisition/sampl e conditioning equipment.

7. Cycle Time and Response Time Test A specification should be incl uded that requires all HCl CEMS to complete at least one cycle of operation (sampling, analyzing, and data recording) for each s uccessive 15-minute period, (i.e., a minimum of four samples per hour). The same considerations apply to time-sharing of HCl monitors as are described above for SO 2 CEMS. A response time test should be conducted according to the procedures described above for SO2 CEMS.

8. Data Reporting Equipment Specifications Additional equipment or designspecifications may be added by st ates to facilitate the specific record keeping and reportin g requirements that may apply. Various state agencies are currently considering a wide range of alternatives including: automat ed data reporting using magnetic media, telecommunication systems tha t allo wagency representatives to obtain or review data on-deman d fromr emote locations, and real-time or intermittent telemetr y systems for CEM data and information. No additional guidance i s incl uded because of the diversity of state requirements an d approaches.SECTION 5

QUALITY ASSURANCE REQUIREMENTS FOR SO2, NOx, CO, HCl CEMS

This section describes the NESCAUM workgroup recommendations for quality assurance requirem ents applicable to SO2, NOx, CO, and HCl CE MS installed at MWC facilities. The NESCAUM workgrou p recommendations are similar to and adopt specific parts of 40 CFR 60, APPENDIX F, PROCEDURE 1. QUALITY ASSURANCE REQUIREMENTS FOR GAS CONTINUOUS MONITORING SYSTEMS USED FOR COMPLIANCE DETERMINATIO N revised July 1, 1988. The QA requirements that are adopted mus t also be consistent with the applicable performance specifications and test procedures. Therefore, the specific NESCAUM workgrou p
reco mmendations for QA requirements and procedures described i n Item s 1 through 8 below reference the corresponding performanc e spe cificationrecommendations in Sections 2, 3, and 4 of thi s document.

The following definition is used: Qualit yassurance consists of the activities and procedures tha t

are perf ormed by the source owner or operator to ensure that CE M data meet certain criteria with respect to accuracy, precision
, availability, and representativeness after the successfu l completion of the initial performance specification test. Specific QA requirements for gas CEMS installed at MWC facilities for the measurement of SO2, NOx, CO, and HCl emission levels an d percent removal are presented in Items 1 through 7 below. 1. Preliminary Monitoring Plan Each source owner or operator required to install a CEMS for the me asurement of one or more gaseous pollutants or diluen t concentrations should submit a preliminary monitoring plan to the agency prior to the installati on of the monitoring equipment. The preliminary monitoring plan need not be submitted if a draft CEMS QA plan is submitted to the agency prior to the installationof the monitoring equipment. Submission of the preliminary monitoring plan is required to provide an opportunity for identification of misunderstanding s between the agency and the sou rce owners or operators with respect to the applicable CEMS requirements and acceptable monitorin g approaches during the planning phase of the monitoring progr am. It is hoped that the submission of such a plan and review by th e agen cywill (1) resolve problems attributable to ambiguou s regula tions, (2) minimize the likelihood of the purchase an d in stallationof unacceptable monitoring equipment, and (3) avoi d the need for development of a detailed quality assurance pla n before actual operating experience with the monitoring equipment is obtained. The preliminary monitoring pla n should very briefly set forththe basic approach that will b e used to comply with the applicable

CEMS requirements. It should include:

a. The identification, location, and description of the specif ic combustor unit(s) (e.g., plant name, unit number, unit size o r capacity, general type of control system, etc.) b. Identificationof the applicable regulations and continuou s monitoring requirements (e.g., EPA NSPS, state regulations, permit requirements, etc.)

c. Identification of the type of monitor (e.g., extractive, poi nt in- situ, etc.) the CEMS manufacturer or vendor, and the mode l

num ber or other identifying feature of the equipment to b e installed d. Identification of the analytical technique for each analyzer that will be used (e.g., NDIR, UV absorption, chemiluminescence, etc.)

e. Identificationand description of the proposed monitorin g location(s) (i.e., position along the effluent path) an d ident ificationof the specific measurement point(s) at eac h monitoring location from which samples will be obtained f. Discussion of plans for time-s haring of extractive monitoring system s between two or more monitoring locations either as a permanent installation or as a back-up provision when a par ticular monitor is inoperative
g. Identification of the procedur es that will be used to convert measurement data to units of the standard, including specifi c conversion factors, assumptions, and equations as applicable h. Description of any mathematical procedures that will be used to co rrect emission measurement data for calibration drift
, interference of other constituents, quenching, or other meas urement phenomena applicable to the proposed measurement system i. Br ief description of the data acquisition system and dat a recording devices j. Identificationof any exceptions to the performanc e specifications or other applic able monitoring requirements and any alternate procedures that may require the approval of the agency

2. CEMS Quality Assurance Plan Eac hsource owner or operator should develop a CEMS qualit y
ass urance plan for each facility. The quality assurance pla n shouldbe submitted to the agency no later than 90 = days afte r completing the initial successful performance specification test of the CEMS. At a minimum the quality assurance plan must addr ess the following specified quality control and quality assessmen t subjects: a. Background information. - - This should include: · Identification and description of the specific combustor unit(s)

· Identification of the applicable regulations and monitorin g requirements · Identification and description of the monitoring instrume ntation · Description of the measurement location(s) and sampling points· Description of the data recording devices and data handlin g

system This information is a reiteration and update of informatio n contained in the preliminary monitoring plan and information that is usually included in the performance specification tes t report(s). It is included to assure that both the user and th e agency a re aware of changes to the original plan and the curren t status of the monitoring program at the facility. b. Procedures used to establi sh proper calibration of the CEMS. - - These procedures should exp lain how the monitoring equipment is adjusted to provide the correc t responses both initially and after
rep airs or corrective action. The procedures should address th e
ca librationof both the components and the overall measuremen t syst em. The procedures should also identify assumed parameter s (i .e., conversion factors, effluent moisture content, etc.) tha t

ar e important to the fundamental calibration of the monitorin g equipment. Procedures for verifying the validity of mathematical proced ures used to correct or adjust the monitoring data shoul d also be included.

c. Procedures used for the routine (daily) zero and upscal e calibrationchecks and criteria for adjustment of the CEMS fo r excessive drift. - - For monitoring systems that use calibration gases for the daily checks, these procedures should describe: · Where the gases are introduced to the measurement system

· How the correct flow rate and pressure for the gas injection s are determined and maintained · The length of time the gases are injected

· The data display device(s) used to determine the monito r response · Any procedures necessary for the interpretation of the data

· The criteria for deciding if adjustments to the monitorin g system are necessary · The action to be taken when adjustments are needed These procedures should include specification of the supplier and type of calibration materials used for the daily calibrationchecks and the method used to establi sh the concentration values of these materials. For mo nitoring systems that use an alternate method fo r performing the routine zero and upscale checks, similar info rmation describing the procedures is required. The specific requirements should be addressed in the written plan submitted when apply ing for approval of the alternate procedure during the performanc e specification test [See also " Item 1. Use of Calibration Gases" in the recommended performance specifications.] d. Procedures used for cylinder gas audits (linearity tests) and relative accuracy tests. - - These procedures should detail ho w the ac curacy assessments are conducted at the specific facility

. The v alues of the two Protocol 1 calibration gases used for th e linearitytest, the supplier, and the steps taken to ensure tha tthe ce rtification is current should be described. The specifi c

pro cedures for introducing the gases to the monitoring system a s described in Item 2. c (above) for the daily checks should also be included. For relative accuracy tests, the test methods to b e used, sampling location/sampling points, duration of samplin g runs, proced ures for converting the reference data to units of th e standard, and CEMS data interpretation/calculation procedure s should be specified. e. Quality control procedures including daily and periodic checks of system or component performance, preventive maintenanc e pro cedures, spare parts inventory, etc. - - These types o f procedures are inherently monitor- and source-specific. However, detailed written procedures an d corresponding data forms have been found to be effective for identifying developing problems an d promot ing consistency and thoroughness in performing daily an d periodic checks of CEMS. Minimum preventive maintenance pro cedures

are us ually specified by the monitor manufacturer and should b e included in the quality assurance plan. The spare parts tha t should be available on site depends on the data availabilit y requir ements, delivery time from suppliers or other sources, an d the li kelihood of failure of individual components; historica l performance is the best indica tor of the parts that may be needed. The quality control procedures should explain the organization of QAresponsibilities among the various departments/groups o r individuals at the facility. f. Corrective action procedures for repair, adjustment, o r replacement of the CEMS or its components. - - Corrective actio n proc edures are often trouble-shooting efforts and are therefor e difficult to describe in suffi cient detail to be useful. However, clear objective criteria for d etermining when corrective action is neededbased on the results of the required daily checks an d period ic accuracy tests should be included. Additional criteri a rela tedto procedures or checks included as quality contro l proced ures may also be helpful in resolving developing problems

. This section should also inclu de alternative monitoring procedures for use when minimum data availability requirements cannot be met by the CEMS.
g. Procedures used for data reduction, record keeping, an d reporting of CEMS information. - - These procedures should detail exactly how the CEMS data is handled including: · methods for correcting data for calibration drift · specific averaging procedures

· methods of excluding invalid data and calibration data fro m emission averages

· equ ations, constants, and assumptions used to conver t concentration measurements to units of the standard · provisions for recording process/control system data and reasons for excess emissions · provisions for recording CEMS downtime, adjustments, and repairs · procedures for review and editing of dataThe media, format, and location of all records and all reports to

be submitted to the agency should be specified. The individ uals or
groups responsible for maintenance of records, development o f reports, and review of reports should be identified.

3. Quality Assurance Plan Revision Eachsource owner or operator should review the QA plan an d all data generated by its implementation at least once each yea r and revise or update the plan, as necessary, based on the results of the ann ual review. The revised plan must be available fo r on-sit e review by the agency at any time. Within thirty days o f completionof the annual QA plan review, the source owner o r operator must submit a writtenexplanation of all changes (or lack of changes) to the agency. The a gency may request revision of the QA plan at any tim e based on the results of emission report reviews, inspections
, audits, review of the QA plan, or any other information available to the agency.

4. Routine Zero and Upscale Calibration Checks Each s ource owner or operator should perform a zero (o r low-level value between 0 = and 20 percent of span) and upscale (50 to 90 percent of span) calibra tion drift check at least once daily inaccordance with a written procedure contained in the CEMS Q A plan. The daily check procedure must provide a check of the entire measurement system including sample acquisition equipment, sample lines, conditioning systems, analyzers, and data recording d evices. The procedure must be accomplished by introducing calibratio n gases of the required concentrations in the sampling probe or at th e sampling probe outlet. For me asurement systems employing dilution probes or similar devices, the calibration gases must be int roduced prior to the dilution point and in such a manner that they ar e diluted to the same extent as the sample gases from the effluen t stream. Similarly, for sample acquisition systems using asp irators

or eductors, the calibration gases must be introduced prior t o these devices even if these components are part of the sampl e probe assembly. The values of the calibration gases may be established through the use of certified reference materials (CRMS), standard refer ence materials (SRMS), or EPA Protocol 1 gases

. Alter natively, calibration gas values determined by the ga s manufacturer's certified analysis (i.e., + 2 % of tag value) may be used if the concentration is checked by direct comparison with Pro tocol 1 gases, or by triplicate analysis using an appropriat e EPAtest method or an equivalent procedure. (See recommende d Perfor mance Specifications for SO2 CEMS, Item 3 for specifi c procedures for establishing the gas concentrations.) Source owners or operators may conduct a demonstration of an altern ate calibration check procedure subject to the approval o f the agency. This demonstration may be conducted during the initial performance specification test or at a later time. (See Sec tion 2,Performance Specifications for SO2 and NOx CEMS 6 , "Item 1. Use of

Calibr ationGases" for guidance on demonstration of an alternat e method.) The monitoring system must allow the amount of positive an d
neg ative drift (difference between the analyzer response an d correct va lue of the calibration gas) to be quantified. At a minimu m, the monitoring system shall be adjusted when the drif t exceed s two times the performance specification limit. (Th e recommendedcalibration drift performance specifications are 2. 5 percent of span for SO2 and NOx monitors, 0.5 = percent O2 or CO2 for diluent monitors, 3 percent of span for CO monitors, and 5 = percent of span for HCl monitors.) When adjustments are made, the drif t check should be repeated after the adjustments are completed t o verify that the monitor responds correctly. The data acquisition system software in some monitorin g systems automatically applies a mathematical correction to t he CEMS emissions data based on the routine zero and span check results

. Some other CEMS utilize an automatic control system for cali bration drift adjustments. Manual adjustment of systems using automati c adjustments is not required until the drift based on the una djusted
responses is equivalent to 10 percent of span for the monitorin g channel. These systems must a llow determination of (1) the amount of drift in the unadjusted values, (2) the magnitude of th e
correc tionfactor or adjustment that is applied, and (3) th e adjusted system response to th e daily zero and upscale calibration values.

5. Cylinder Gas Audit A cylinder gas audit (linearity test) should be performed ea ch calendar quarter using the same procedures and gas specifications that were used during the initial performance specification test. The audit should use the two a udit points specified by Appendix F, Procedure 1 in conjunction with the zero and upscale calibration points used for the daily checks. If the high range audit poin t (i.e., 50 to 60 percent of the pollutant monitor span) of Pr ocedure 1 is used for the daily upscale checks, an audit gas of 80 to 9 0 percent of span should be substituted for the high range audi t point. A three-point audit check is required for HCl monitors

. The same specification used in the performance specification test should also apply for the quarterly audits. Acceptable perf ormance is indicated if the mean difference between the monitor responses and the value of the calibration gas is less than 5 percent of span at eac h of the four audit points for SO2, NOx, CO, and HC l monitors. The acceptance criteria for diluent monitors is 0. 5 percent O2 or CO2. If the system fails the cylinder gas audit
, take corrective action and rep eat the audit until successful. The results of the cylinder gas au dit should be reported to the agency with the emissions report for the period during which the audit is conducted.6. Relative Accuracy Tests

Arelative accuracy test (minimum of nine sampling runs ) shouldbe performed at least once per year using the sam e procedures and specifications used in the initial performanc e specification test. The relative accuracy test should be co nducted as soon as practical before or after one of the quarterly cylinder
gas audits to demonstrate the validity of the gas calibratio n technique and verify assumptions about the calibration procedure. No adjustments or repairs to the monitoring system other than the routine calibration drift adjustment according to the writte n procedure contained in the QA plan can occur between the cylinder gas audit and the relative accuracy test. To be considered working properly, the CEMS must satisfy both the relative accuracy an d cylinder gas audit specifications. If the system fails to mee t either specification, take cor rective action and repeat both tests until successful. The results of the relative accuracy test should be reported to the agency with the emissions report for the period during which the test is conducted.

7. Out-of-Control Periods Crit eria for "out-of-control" periods are similar to thos e defined in Appendix F, Procedure 1. Specifically, the monitor is out-of-control if (a) the calibration drift exceeds two times the
pe rformance specification drift limit for five consecutive days
, (b) = the calibration drift exceeds five times the performanc e specificationlimit on any day, (c) the system fails a relativ e accuracytest, or (d) the monitor fails a cylinder gas audi t des cribed above in Item 5. Data collected during out-of-contro l peri ods cannot be used to satisfy minimum data availabilit y requirements.

8. Minimum Data Availability Requirements Source owners and operators subject to continuous monitoring

re quirements should properly operate and maintain all monitorin g equipment at all times that the source is operational. For sources where gas CEMS are required for the measurement of controlled o r
un controlled emissions of SO2, NOx, CO, or HCl, continuou s monitoring data in units of th e standard should be available for a minimumof 90 percent of the source operating hours for eac h reporting period (e.g., quarterly). For the purpose of dete rmining conf ormance with this requirement, the time required to perfor m
ro utine (e.g., daily) zero and upscale calibration checks, an d quarterly linearity tests is included as CEM operating time. The ti me required for scheduled or unscheduled CEMS maintenance o r othe r quality assurance activities is not included as operatin g time in the determination of CEMS availability except as may b e speci ficallyallowed in a QA plan approved by the agency. Som e states may require higher levels of CEMS data availability or may require the use of redundant monitoring devices for all or som e monitoring parameters.Inthe event that the installed CEMS can not achieve th e

minimum data availability requirement, the source owner or o perator should use alternate monitoring procedures (e.g., back-up mo nitors,
para meter monitoring, performance testing, etc.) subject to th e app roval of the agency. The alternate monitoring procedures ar e required to be described in the QA plan. (See Section 5, 2 Quality Assurance Plan Item f.)SECTION 6

EQUIPMENT AND PERFORMANCE SPECIFICATIONS FOR OPACITY CEMS AT MUNICIPAL WASTE COMBUSTION FACILITIES

This section describes the NESCAUM workgroup recommendations for monitor location requirements, design specifications
, performance specifications, and corresponding test procedures for opacit yCEMS installed at MWC facilities. Specifically, th e NESCAUM workgroup recommends t hat states consider adopting the EPA requirements contained in "PERFORMANCE SPECIFICATION 1

- SPECIFICATION AND TEST PROCEDURES FOR OPACITY CONTINUOUS EMISSION MONITORING SYSTEMS IN STATIONARY SOURCES" of 40 CFR 60, Appendix B revised July 1, 1988, with the changes detailed in Items 1 through 5 below.

1. Performance Specification 1 Design Specifications The design specifications in Performance Specification 1 should be adopted for: peak and mean spectral response, angle of view, angle of projection, opt ical alignment sight, simulated zero and up scale calibration checks, access to external optics, an d automa tic zero compensation indicator. In addition, "Section 6

. DesignSpecification Verification Procedure" of Performanc e Spe cification1 should be used to determine conformance with th e above design requirements. The optional requirement in Perf ormance Specification 1, "Section = 5.1.9 External Calibration Filter Access" sho uldbe changed to a mandatory requirement to ensure th e capability of auditing the monitor using external calibratio n attenuators. (Note: The EPA Atmospheric Research and Exposure Assessment Laboratory, Quality Assurance Division has initiated an evaluation of the procedures used for the manufacturer's certification o f

co nformance with the design specifications for opacity monitors

. Rev isionof Performance Specification 1 requirements or tes t procedures may also result fro m this effort. Among others, future

rev isions may include (1) test procedure clarifications, (2 )
sp ecifications for uniformity of light beam, (3) specifi c procedures for checking the photopic response.)

2. Cycle Time and Measurement Frequency An additional design specifica tion should be added to require that all opacity monitors complete a minimum of one cycle o f sampling and analyzing for each successive 10-second period and one cycle of data recording for each successive 6-minute period o r other period as specified in applicable regulations during normal operation. This requirement is similar to the requir ement in 40 CFR 60.13 (e ) (1) and is also consistent wit h the response time specification in Performance Specification1. Thespecif icationshould require that the opacity monitoring syste m

have the capability to display measurements for 1-minute per iods or shorter intervals to facilitate monitor performance evaluations.

3. Data Availability and Back-Up Data Recording Devices Al l opacity CEMS must operate continuously without repairs
, unscheduledmaintenance, or non-routine adjustments during th e perfo rmance specification tests. In addition, minimum dat a avai labilityspecifications are included as a quality assuranc e requirements and are applicabl e to the operation of the CEMS after completion of the performance specification tests. (See Sec tion 7, Quality Assurance Requirements for Opacity CEMS, 8. Minimum Data Availability Requirements.) It is recognized that most MWC CEMS will include a compute r data acquisition system and that when the data acquisition system is inoperative, many vital CEMS functions are suspended and dat a availability is immediately af fected. Source owners and operators

are encouraged, but not required, to include a back-up recordin g device or other appropriate re dundancy within the data acquisition system in order to maximize data availability.

4. Performance Specification 1 Performance Test Procedures an d Acceptance Criteria The Performance Specification 1 criteria should be adopted f or calibration error, response ti me, conditioning period, operational test period, and zero and calibration drift. In addition, Section 7,. Performance Specification Verification Procedure should be used to d etermine conformance with these criteria. However, th e requirement that allows the ca libration error test to be performed either at the manufacturer's facility or in the field should b e changed. The regulation shoul d allow the source owner or operator to choose either (1) to conduc t the calibration error tests in the field, or (2) to conduct a per formance audit of the monitor during the operational test period to ensure that calibration error test results obtained at the manufa cturer's facility are representative of i nstalled CEMS performance. Procedures for conducting a perf ormance audit are included with the opacity monitor qualit y assurance requirements.

5. Data Reporting Equipment Specifications Additional equipment or designspecifications may be added by st ates to facilitate the specific record keeping and reportin g requirements that may apply. Various state agencies are currently considering a wide range of al ternatives including: automated data reporting using magneti c media, telecommunication syste ms that allow agency representatives to obtain or review data on-demand from remote locations, an d real-t ime or intermittent telemetry systems for CEM data an d inform ation. No additional guidance is included because of th e diversity of state requirements and approaches.SECTION 7

QUALITY ASSURANCE REQUIREMENTS OPACITY CEMS

This section describes the NESCAUM workgroup recommendations for QArequirements applicable to opacity CEMS installed at MW C facilities. The QA requirements that are adopted should b e consistent with the applicable performance specifications and test procedures. Therefore, the specific NESCAUM workgrou p
reco mmendations for QA requirements and procedures described i n Item s 1 through 7 below reference the performance specificatio n recommendations in Section 6 of this document.

The following definition is used: Qualit yassurance consists of the activities and procedures tha t

are perf ormed by the source owner or operator to ensure that CE M data meet certain criteria with respect to accuracy, precision
, availability, and representativeness after the successfu l completion of the initial performance specification test.

The following QA requirements are recommended for opacity CEMS: 1. Preliminary Monitoring Plan Each source owner or operator required to install an opacity CEMS should submit a preliminary monitoring plan to the agenc y prior to the installation of the monitoring equipment. Th e preliminary monitoring plan need not be submitted if a draft CEMS qualityassurance plan is submitted to the agency prior to th e installation of the monitoring equipment. Submission of the preliminary monitoring plan is required to provide an opportunity for identification of misunderstanding s between the agency and the sou rce owners or operators with respect to the applicable CEMS requirements and acceptable monitorin g approaches during the planning phase of the monitoring progr am. It is hoped that the submission of such a plan and review by th e agen cywill (1) resolve problems attributable to ambiguou s regula tions, (2) minimize the likelihood of the purchase an d in stallationof unacceptable monitoring equipment, and (3) avoi d the need for development of a detailed quality assurance pla n before actual operating experience with the monitoring equipment is obtained.

The plan should very briefly set forth the basic approach th at will be used to comply with the applicable monitoring requir ements. It should include:

a. The identification, location, and description of the specif ic combustor unit(s) (e.g., plant name, unit number, unit size o r capacity, general type of control system, etc.)b. Identificationof the applicable regulations and continuou s

monitoring requirements (e.g., EPA NSPS, state regulations, permit requirements, etc.)

c. Identification of the CEMS manufacturer or vendor, the model

num ber or other identifying feature of the equipment to b e installed d. Identification of the proposed monitoring location(s) (i.e.,
pos itionalong the effluent path), description of th e transmissometer measurement path orientation at each monitorin g location, measurement path length, and stack exit diameter

e. Dis cussionof procedures and equipment that will be used t o calc ulate the opacity of emissions discharged to the atmospher e where two or more transmissome ters are installed in multiple ducts for a single unit or where emissions from multiple units ar e exhausted through a common stack f. Description of any automatic procedures that will be used to correct or adjust opacity measurement results for calibratio n drift
g. Description of the data recording devices that will be used h. Identificationof any exceptions to the performanc e specifications or other applic able monitoring requirements and any alternate procedures that may require the approval of the agency

2. CEMS Quality Assurance Plan Eachsource owner or operator should develop a CEMS QA pla n for each facility. The QA plan should be submitted to the agency

no t later than 90 = days after completing the initial successfu l performa nce specification test of the CEMS. At a minimum the Q A plan must address the following quality control and qualit y assessment subjects:

a. Background information. - - This should include: · Identification and description of the specific combustor unit(s)

· Identification of the applicable regulations and monitorin g requirements · Identification and description of the monitoring instrume ntation · Description of the measurement location(s) and monitor paths

· Description of the data recording devices and data handlin g system. This information is a reiteration and update of informatio n contained in the preliminary monitoring plan and information that is usually included in the performance specification tes t report(s). It is included to assure that both the user and th e agency a re aware of changes to the original plan and the curren t status of the monitoring program at the facility. b. Procedures used to establish proper calibration of the CEMS. - - These procedures should explain how the monitoring equipment is adjusted to provide the correc t responses both initially and after
rep airs or corrective action. The procedures should address th e calibration of the transmissom eter(s), the data recording devices, and the overall measurement system. Procedures for verifying the validity of mathematical corrections or other automatic adju stmentsto the monitoring data should be included.

c. Procedures used for the routine (daily) zero and upscal e calibrationchecks and criteria for adjustment of the CEMS fo r excessive drift. - - These procedures should explain: · How the daily calibration checks are initiated

· The data display device(s) used to determine the monito r responses,

· The criteria for deciding if adjustments to the monitorin g system are necessary · The action to be taken when adjustments are needed It is particularly important that any assumptions associated with t he calibration check procedure be understood and that an y auxiliarymonitor parameters necessary to assess monito r performance be identified. d. Procedures for performance audits and zero alignment checks.

- - These procedures should provide any special informatio n
ne cessaryfor the conduct of performance audits or th e inte rpretationof the audit results. Zero alignment procedure s should explain how the monitor is removed from the stack andset up under clear path conditions or how the test is performed on th e installed monitor during source outages. The specific procedures used to adjust the simulated zero device and the records of th e zero alignment results and adjustments should be explained.

e. Quality control procedures including daily and periodic chec ks of sy stem or component performance, preventive maintenanc e pro cedures, spare parts inventory, etc. - - These procedures ar e inherently monitor- and source-specific. However, detailed written
pro cedures and corresponding data forms have been found to b e effective for identifying developing problems and promotin g consistency and thoroughness in performing daily and periodi c checks of monitoring systems. Minimum preventive maintenanc e proced ures are usually specified by the monitor manufacturer an d should be included in the qual ity assurance plan. The spare parts that should be available on site depends on the data availability requir ements, delivery time from suppliers or other sources, an d the li kelihood of failure of individual components; historica l performance is the best indica tor of the parts that may be needed. The quality control procedures should explain the organization of QAresponsibilities among the various departments/groups o r individuals at the facility. f. Corrective action procedures for repair, adjustment, o r replacement of the CEMS or its components. - - Corrective actio n proc edures are often trouble-shooting efforts and are therefor e difficult to describe in suffi cient detail to be useful. However, clear objective criteria for d etermining when corrective action is neededbased on the results of the required daily checks an d periodic audits should be included.

g. Pro cedures used for data reduction, record keeping, an d reporting of CEMS information. - - These procedures should detailexactly how the CEMS data is handled including:

· methods for correcting data for calibration drift, if app licable · criteria for identifying invalid data · provisions for recording process/control system data and reasons for excess emissions; · provisions for recording an d tracking CEMS downtime adjustments and repairs. The media, format, and location of all records and all repor ts to be submitted to the agency should be specified. The indi viduals

or gro ups responsible for maintenance of records, development o f reports, and review of reports should be identified.

3. Quality Assurance Plan Revision Eachsource owner or operator should review the QA plan an d all data generated by its implementation at least once each yea r and revise or update the plan, as necessary, based on the results of the ann ual review. The revised plan must be available fo r on-sit e review by the agency at any time. Within thirty days o f completionof the annual QA plan review, the source owner o r operator must submit a writtenexplanation of all changes (or lack of changes) to the agency. The a gency may request revision of the QA plan at any tim e based on the results of emission report reviews, inspections
, audits, review of the QA plan, or any other information available to the agency.

4. Routine Zero and Upscale Calibration Checks Each s ource owner or operator should perform a zero (o r low-level value between 0 = and 20 percent of span) and upscale (50 to 90 percent of span) calibra tion drift check at least once daily inaccordance with a written procedure contained in the CEMS Q A plan. (This requirement is the same as that contained in 40 CF R 60.13 (d) = (1).) The daily check procedure must provide a syste m check of the analyzer internal optical surfaces and all electronic circuitry including the lamp and photodetector assembly. The monitoring system must allow the amount of positive an d
neg ative drift (difference between the analyzer response an d correct value of the calibration check devices) to be quantified. At a minimum, the monitoring system shall be adjusted when th e drift exceeds the performance specification limit, i.e., 2 percent opacity. (This criteria is twice as restrictive as the crit eria in 40 CFR 60.13.) The transmissometer optical surfaces exposedto the effluent should be cleaned prior to performing the zero an d

ca librationdrift adjustments except for systems using automati c zero adjustments. When calibration adjustments are made, th e drift check should be repeated after the adjustments are completed t o verify that the monitor responds correctly. Some opacity monitors use an automatic zero compensatio n device to offset dust accumulation on the optical surfaces o r other ch anges in the electro-optical components. Also, the dat aacquisitionsystem software in some monitoring system s

automatically applies a mathematical correction to the monitoring dat a based on the zero and upscale calibration check results

. Manual adjustment of systems u sing automatic adjustments should be performed when the drift basedon the unadjusted responses (or the
mag nitude of the adjustment) is equivalent to 4 percent opacity

. These systems must allow determination of the amount of drift i n the un adjusted values or the magnitude of the correctio n factor/adjustment that is applied.

5. Performance Audit A performance audit of each opacity CEMS should be performed

ea chcalendar quarter according to the procedures contained i n "Performance Audit Procedures for Opacity Monitors " EPA-600/8-87-025, April 1987, or equivalent procedures subject to the approval of the agency. The criteria contained in th e ref erenced document for stack exit correlation error, syste m faults, zero and span errors, monitor alignment, dust accumu lation, and ca libration error should be used to determine acceptabl e perfor mance. The results of the performance audit should b e reported to the agency with the emissions report for the perio d during which the audit is conducted. The values of the optical filters used in performance audits shouldbe checked at least once per year according to th e procedures in Performance Specification 1.

6. Zero Alignment
Azero alignment should be performed at least once per yea r unless a particular facility can submit data showing that a different frequency is appropriate. The zero alignment procedure involves adjustment of the monitor so that the response to th e simulated zero device coincides with the monitor response t o clear pathconditions. The check may be accomplished if clear pat h conditions are present during a source outage or by removing th e transmissometer from the stack and setting up the instrument at the operating pathlength in a clean environment. (General procedures for performing zero alignment checks are described in Section 9 of "Performance Audit Procedures for Opacity Monitors.") The amount of adjustment necessary to accomplish the zero alignment (expressed

as percent opacity) should be reported to the agency with th e emi ssions report for the period during which the procedure i s conducted. An external, removable, zero-jig may be used as an alternate procedure to the zero alignment provided that (1) the zero-ji g set ting is established for the specific monitor by comparison o f monitor responses to the zero- jig and to the clear path condition, (2) the zero-jig is demonstrated to be capable of producing a consistent zero response when it is repeatedly reinstalled on the monitor, a nd (3) the zero-jig is protected when not in use t o ensure that the setting equivalent to the zero condition does notchange. Source owners or operators that use a zero-jig shoul d

perform a zero alignment and check of the zero-jig at least onc e every three years.

7. Out-of-Control Periods Crit eria for "out-of-control" periods are similar to thos e defined for gas CEMS. Specifically, an opacity monitor should be considered out-of-control if ( a) the calibration drift exceeds the performance specification drift limit (i.e., 2 percent opaci ty) for five consecutive days, (b) the calibration drift exceeds fiv e percent opacity on any day, or (c) the opacity monitoring syste m fails a performance audit. Data collected during out-of-contro l peri ods cannot be used to satisfy minimum data availabilit y requirements.

8. Minimum Data Availability Requirements Source owners and operators subject to continuous monitoring

re quirements should properly operate and maintain all monitorin g equipment at all times that the source is operational. For sources where opacity CEMS are require d, continuous monitoring data should be avail able for a minimum of 90 percent of the source operatin g hours for each reporting period (e.g., quarterly). For the purpose of determining conformance with this requirement, the time r equired to perform routine (e.g., daily) zero and upscale calibratio n chec ks, and quarterly performance audits is included as CE M operat ing time. The time required for scheduled or unschedule d CEM S maintenance or other QA activities is not included a s operating time in the determin ation of CEMS availability except as
may be s pecifically allowed in a QA plan approved by the agency

. Some states may require higher levels of CEMS data availability.
Inthe event that the installed CEMS can not achieve th e minimum data availability requirement, the source owner or o perator should use alternate monitorin g procedures subject to the approval of the agency.APPENDIX

Comparison of Accuracy Specifications

The two basic relative accurac y specifications of Performance Specification 2 are illustrated in Figure 1. It can be seen that "20 pe rcent of the reference value" is the least restrictiv e criterion when the emission level is greater than 50 percent of the standard; "10 percent of the standard" becomes the less rest rictive criterion when the emissions a re below 50 percent of the standard. For both of these specifications, the relative accuracy calc ulation includes the sum of the mean difference plus 95% confidenc e coefficient. The recommended 5 ppm mean difference criterion is an absolu te accuracy specification similar to the "10 percent of the standard" specification. The 5 ppm criterion is less restrictive than th e "10 percent of the standard" criterion when the emission standard is 50 ppm because the confidence coefficient is eliminated. A t lower emission standards the difference between the two criteri a becomes more significant and the 5 ppm criterion is the les s restri ctive. The various relative accuracy specifications ar e illustratedin Figure 2 for emission standards of 50 = ppm and 3 0 ppm. The recommended 5 ppm mean difference accuracy specif ication attempts to reflect the limitations associated with the reference test procedures, the CEMS meas urement capability, and the relative accuracy tests at sources with fluctuating emission levels. These technical limitations are inde pendent of the level of the emission standard. Similarly, the 5 ppm criterion is also independent o f the level of the emission standard. It can be shown that the propo sed NSPS MWC SO2 emission limit of 30 ppm corrected to 7 perce nt O2 corresponds to about 0.07 lbs. SO2/MMBtu. Thus, the alternate "20 percent of the standard "

accura cyspecification of Performance Specification 2 could b e applie d. However for the proposed NSPS standard, this limi t corresponds to 6 ppm and includes the confidence coefficient . This is pro bably more restrictive than the recommended 5 ppm mea n difference criterion without the confidence coefficient and it is als o dependent on the emission standard. The "average" o r "typi cal" contribution of the confidence coefficient to th e relat ive accuracy result could be determined by statistica l analysis of test results at MWC facilities. However, it seem s unlikely that the confidence c oefficient contribution is less than 1 ppm. Thus, the 5 ppm mean difference limit is less restrictive than the "20 percent of the standard" criteria.Figure 1. Performance Specification 2,Relative Accuracy Specifications ACTUAL EMISSIONS

(Percent of Standard) 10 20 30 40 50 60 70 80 90 100 10 20 30 40 50 60 70 80 90 100 110 120

Figure 1 Redrawn to be compatible with Wordperfect fileNOTE: I had to redraw the foll owing figures because they were done orginally on a MAC. They are not quite as precise as they should be. If you want a hard copy of the orginals, send me a Message on the BBS . Terry Harrison30 ppm

STD

30 ppm STD
Transition +
(assumes 2.5 ppm confidence coefficient) Equivalent 5 ppm Mean Difference Accuracy Criterion

- 10 % of 50 ppm STD (i.e. 5 ppm) +

-

10% of 30 ppm STD (i.e. 3 ppm) +

- 50 ppm STD

Transition 50 ppm
STD

+

-

10 20 30 40 50 60 70 80 ACTUAL EMISSIONS (ppm) Figure 2. Example Accuracy Specifications for 30 ppm and 50 ppm Standards

10 20 30 40 50 60 70 80

Figure 2 Redrawn to be compatilbe with Wordperfect file.