# Regulations

Titles of Regulations; 9VAC5-40. Existing Stationary 

### Sources (amending 9VAC5-40-20) 9VACS-5O, New and Modified Stationary Sources (amending 9VAC5-50-20). Statutory Authority; §10.1-1308 of 

### the Code of Virginia; §110, 111, 123, 129, 171, 172 and 182 ofthe Clean AirAct; 40 CFRParts 51 and 60. EffectiveDate; December 12, 2007. Agency Contact: Mary E. Major, Department of Environmental Quality, 629 EastMain Street, P.O. Box 1105, Richmond, VA 23218, telephone (804) 698-4423, FAX (804) 698-4510, oremail memajordeq.virginia.gov. Summax-yj

The special provisions of the regulations concerning existing/new andmod/iedstaIionaysources are amended to incorporate therequirements ofChapter 148ofthe2007 Acts ofAssemby. Specflcally. 9VAC5-40-20 A 3 and 9VAC5$0-20A 3 areamendedto indicatethatcompliance with opacity znay be determined in one ofthefollowing ways: (i) compliance with Reference Method 9 or any alternative method approved by EPA, () evaluation of dataresultingfromuseofcntinuous 

### monitoringproviding that certain criteria are met, or (iii) use ofany other methodapprovedbyEPA. 9VAC5-40-20. Compliance. A. Ninety days alter the effective date of any emission standard prescribed under this chapter, no owner or other person shall operate any existing source in violation ofsuch standard.

1. Compliance with standards in this chapter, other than opacity standards, shall be detennined by emission tests establishedby 9VAC5-40-30, unless specified otherwise in the applicablestandard. 2. Compliance with federal requirements in this chapter may be determined by alternative or equivalent methods only ifapprovedby the administrator. Forpurposes ofthis subsection, federalrequirements consist ofthefollowing;

a. New source performance standards established pursuantto 

### § 111 ofthe federal CleanAirAct. b. Alltemis and conditions in afederal operating permit, including any provisions that limit a source’s potential to emit, unless expressly designated as not federally enforceable.

c. Limitations and conditions that are part of an implementation plan. d. Limitations and conditions that are part of a section 111(d) or section 111(d)/129 plan.

e. Limitations and conditions that are part of a federal construction permit issued under 40 CFR. 52.21 or any constructionpermit issuedunderregulations approvedby EPA in accordance with40 CER Part 51. f. Limitations and conditions that are part ofan operating permit issued pursuant to a program approved by EPA into an implementation plan as meeting EPA’s minimum criteria for federal enforceability, including adequate notice and opportunity for EPA and public comment prior to issuance of the final permit and practicable enforceability. 3. Compliance with opacity standards in this chapter shall in be determined by conducting one or more of the following means;

a Conducting observations in accordance withReference Method 9 or any alternative method approved by EPA. For purposes of determining initial compliance, the minimum total time ofobservations shall be three hours (30 six-minute averages) forthe emission test orother set of observations (meaning those fugitive-type emission
sources subject only to an opacity standard). Opacity readings ofportions ofplumes which contain condensed, uncombined water vapor shall not be used for purposes ofdetermining compliance with opacity standards.
b. Evaluation of data resulting from use ofcontinuous monitoring by transmissometer, provided the instrument

Volume24, Issue 5 VirginiaRegisterofRegulations November 12, 2007 

### Final Regulation
REGISTRAR’S NOTICE; The State Air Pollution Control Board has claimed an exemption from the Administrative Process Act in accordance with §2.2-4006 A 4 a ofthe Code ofVirginia, which excludes regulations that are necessary to conform to changes in Virginia statutory law or the appropriation act where no agency discretion is involved. The State Air Pollution ControlBoard will receive, consider andrespond to petitions by any interestedperson at any time withrespectto reconsideration orrevision.

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used meets Performance Specification I in Appendix B of40 CFR Part 60 andhas been properly maintained and that theresl]ltina datahave notbeen altered in anyway.

c. Use ofany othermethodapprovedby EPA. 4. The opacity standards prescribedunderthis chaptershall apply at all times except during periods of startup, shutdown, malfunction, and as otherwise provided in the applicable standard. This exception shall not apply to the following federalrequirements:

a. Limitations and conditions that are part of an implementationplan. b. Limitations and conditions that are part ofa federal construction permit issued under 40 CFR 52.21 or any constructionpermit issuedunderregulations approvedby EPA in accordancewith40 CFRPart 51.

c. Limitations and conditions that arepartofan operating permit issued pursuant to a program approved by EPA into an implementation plan as meeting EPA’s minimum criteria for federal enforceability, including adequate notice and opportunity for EPA and public comment prior to issuance of the final permit and practicable enforceability. B. No owner ofan existing source subject to the provisions ofthis chaptershall fail to conduct emission tests as required underthis chapter.

C. No owner ofan existing source subject to the provisions of this chapter shall fail to install, calibrate, maintain and operate equipment for continuously monitoring andrecording emissions or process parameters or both as required under this chapter.

D. No owner ofan existing source subject to the provisions ofthis chapter shall fail to provide notifications and reports, revise reports, maintain records or report emission test or monitoring results as requiredunderthis chapter.

E. At all times, including periods ofstartup, shutdown, soot blowing and malfunction, owners shall, to the extent practicable, maintain and operate any affected facility including associated air pollution control equipment in a manner consistent with air pollution control practices for minimizing emissions. Determination ofwhether acceptable operating and maintenance procedures are being used will be based on information available to the board, which may include, but is not limited to, monitoring results, opacity observations, review of operating and maintenance procedures, and inspection ofthe source.

F. At all times the disposal ofvolatile organic compounds shall be accomplished by taking measures, to the extent practicable, consistent with airpollution control practices for minimizing emissions. Volatile 

### organic compounds shall not be intentionally spilled, discarded in sewers which are not connectedto atreatmentplant, orstored in open containers or handled in any othermannerthat wouldresult in evoration beyond that consistentwith airpollution control practices for minimizing emissions.

G. The following provisions apply with respect to demonstrating compliancewith opacity standards.

1. For the purpose of demonstrating initial compliance, opacity observations shall be conducted concurrently with the initial emission test unless one of the following conditions apply:

a. If no emission 

### test is required, then opacity observations shall be conducted within 60 days after achieving the maximum production rate at which the affected facility will be operated but no later than 180 days afterthe compliance date. b. If visibility or other conditions prevent the opacity observations from being conducted concurrently with the initial emission test, the owner shall reschedule the opacity observations as soon afterthe initial emission test as possible, but not later than 30 d’s thereafter, and shall advise the board ofthe rescheduled date. In these cases, the 30-day priornotification to the board required by 9VAC5-40-50 A 3 shall be waived. The rescheduled opacity observations shall be conducted (to the extent possible) under the same operating conditions that existed during the 

### initial emission test. The visible emissions observer shall determine whether visibility or other conditions prevent the opacity observations from being made concurrently with the initial emission test in accordance with procedures contained in Reference Method 9. Opacity readings of portions of plumes which contain condensed, uncombined water vapor shall not be used for purposes of determining compliance with opacity standards. The owner of an affected facility shall make available, upon request by the board, such records as may be necessary to determine the conditions underwhich the visual observations were made and shall provide evidence indicating proof of current visible observer emission certification. The results of continuous monitoring by transmissometerwhich indicate thatthe opacity at the time visual observations were made was not in excess ofthe standard are probative but not conclusive evidence ofthe actual opacity of an emission, provided the source meets the burden ofproving that the instrument used meets (at the time of the alleged violation) Performance Specification 1 in Appendix B of40 CFR Part 60 andhas been properly maintained and (at the time ofthe alleged violation) that the resulting data have not been altered in any way. 2. Except as provided in subdivision 3 ofthis subsection, the owner of an affected facility to which an opacity

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standard in this chapter applies shall conduct opacity observations in accordance with subdivision A 3 ofthis section, shall record the opacity of emissions, and shall reportto the boardthe opacityresults 

### along with the results ofthe initial emission test. The inability of an owner to
secure avisible emissions observer shall notbe considered
a reason for not conducting the opacity observations concurrentwith the initial emissiontest. 3. The owner of an affected facility to which an opacity standard in this chapter applies may request the board to determine and to recordthe opacity ofemissions from the affectedfacility during the initial emission test and at such times as may be required. The owner of the affected facility shall report the opacity results. Any request to the board to detennine and to record the opacity ofemissions from an affected facility shall be included in the notification required in 9VACS-40-50 A 3. i1 for some reason, the board cannot detennine and record the opacity ofemissions from the affectedfacility during the emission test, then the provisions ofsubdivision 1 ofthis subsection shall apply. 4. An owner of an affected facility using a continuous opacity monitor (transmissometer) shall record the monitoring data produced during the initial emission test and shall furnish the board a iitten report of the monitoring results along with the Reference Method 9 and initial emission testresults.
H. The following provisions apply with respect to new or more stringent emission standards: 1. The following provisions apply withrespect to emission standards forvolatile organic compounds:

a. In the case of any emission standard for volatile organic compounds adopted by the board which is more stringent than the emission standard for the source in effect prior to such adoption, ifany, or where there was no emission standard, the source shall not be considered in violation of the newly adopted emission standard providedthatthe owneraccomplishesthe following: (1) Complies with the emission standard as expeditiously
as possible but in no case later than one year after the effective date ofthe emission standard. (2) Within one month ofachieving compliance, notifies theboard ofsame. (3) Within six months of achieving compliance, demonstrates to the satisfaction ofthe board compliance with the emission standard. b. The reprieve provided by subdivision 1 a of this subsection shall only apply in cases where it is necessary forthe ownerto: (1) Install emission control equipment or other equipment that alters the facility in orderto comply with the emission standard; or (2) Switch fuel or raw materials or both in order to comply with the emission standard.

c. Owners ofsources not in compliance with the newly adopted emission standard, but in compliance with the provisions ofsubdivision 1 aofthis subsection shall not be subject to any penalties for violation of the newly adopted emission standard that may be required by the VirginiaAirPollution Control Law. d. Any reprieve from the sanctions ofany provision of the Virginia Air Pollution Control Law pursuant to subdivision 1 aofthis subsection shallnot extendbeyond the date by which compliance is tobe achieved.

e. Nothing in subdivision 1 a ofthis subsection shall prevent the board from promulgating a separate compliance schedule for any source ifthe board finds that it is technologically infeasible or it is infeasible due to the nonavailabiity of necessary equipment or materials or other circumstances beyond the owner’s control for the source to achieve compliance within one yearofthe effective date ofan emission standard. f. All compliance schedules proposed orprescribedunder this section shall provide for compliance with the applicable emission standards as expeditiously as practicable.

g. Any compliance schedule approved under this subsection may be revoked at any time if the source owner does not meet the stipulated increments of progress, and ifthe failure to meet an increment is likely to result in failure to meet the date for final compliance, and the failure to meet the increment is due to causes withinthe owners control. 2. The following provisions apply withrespectto emission standards for pollutants other than volatile organic compounds:

a. In the case ofany emission standard adopted by the boardwhich is more stringent than the emission standard forthe source in effect prior to such adoption, ifany, or where there was no emission standard, the source shall not be considered in violation of the newly adopted emission standard providedthat the owner accomplishes the following: (1) Submits in a form and manner satisfactory to the board, a control program showing how compliance shall be achieved within the time frame in the applicable compliance schedule prescribed under 9VAC5-40-21; or, where no applicable compliance schedule is prescribed under 9VAC5-40-21, how compliance shall be achieved
as expeditiously as possible; but in no case later than

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three years after the effective date of such emission standard. (2) Receives approval of the board of such control program. (3) Complies with all provisions, terms and conditions of the control program including the increments ofprogress. b. The reprieve provided by subdivision 2 a of this subsection shall only apply in cases where it is necessary forthe ownerto: (1) Install emission control equipment or other equipmentthat alters the facility in orderto comply with the emission standard; or (2) Switch fuel or raw materials or both in order to comply withthe emission standard.

c. Owners ofsources not in compliance with the newly adopted emission standard, but in compliance with the provisions ofsubdivision 2 a ofthis subsection shall not be subject to any penalties for violation ofthe newly adapted emission standard that may be required by the VirginiaAirPollution Control Law. d. Any reprieve from the sanctions ofany provision of the Virginia Air Pollution Control Law pursuant to subdivision 2 aofthis subsection shallnot extendbeyond the date, specified in the emission standard or approved controlprogram, by which compliance isto be achieved.

e. Control programs submitted under the provisions of subdivision 2 a ofthis subsection shall be processed in accordance with the provisions of 9VAC5-20-170. However, ifthe control program contains a compliance schedule which conforms to the applicable schedule prescribedin 9VAC5-40-21, thepublic hearing provision of9VACS-20-170 shall not apply. £ Nothing in this section shall prevent the board from promulgating a separate compliance schedule for any source if the board finds that the application of a compliance schedule in 9VACS-40-21 is technologically infeasible, or ifthe board finds that the application ofa compliance schedule in 9VAC5-40-21 is infeasible due to the nonavailability of necessary equipment or materials or other circumstances beyond the owner’s control.

g. Nothing in this section shall prevent the owner of a source subject to acompliance schedule in 9VAC5-40-21 from submitting to the board a proposed alternative compliance schedule provided the following conditions
are met: (1) The proposed alternative compliance schedule is submitted within six months ofthe effective date ofthe emission standard; (2) Thefinal controlplans forachieving compliance with the applicable emission standard are submitted simultaneously; (3) The alternative compliance schedule contains the
same increments ofprogress as the schedule forwhich it is proposed as an alternative; and (4) Sufficient documentation is submitted by the owner ofthe source tojustifi the alternative dates proposed for the increments ofprogresa h. All compliance schedules proposed or prescribed underthis section shall provide for compliance with the applicable emission standards as expeditiously as practicable. i. Any compliance schedule approved under this subsection may be revoked at any time if the source owner does not meet the stipulated increments of progress, and ifthe failure to meet an increment is likely to result in failure to meet the date for final compliance, and the failure to meet the increment is due to causes within the owner’s control. 

## j. The provisions of 9VAC5-40-21 shall not apply to owners of sources which are in compliance with the applicable emission standard and for which the owners have determined and certified compliance to the satisfaction of the board within 12 months of the effective date ofthe applicable emission standard. I. The following provisions apply with respect to stack heights: 1. The degree ofemission limitationrequiredofany source ownerfor control ofany airpollutant shall notbe affected in any mannerby:

a So much ofthe stackheight ofany source as exceeds good engineering practice; or b. Any otherdispersion technique. 2. The provisions ofsubdivision 1 ofthis subsection shall notapply to:

a Stack heights in existence, or dispersion techniques implemented on or before December 31, 1970, except where pollutants are being emitted from such stacks or using such dispersion techniques by sources, as defmed in §111(aX3) ofthe federal Clean Air Act, which were constructed, or reconstructed, or for which major modifications, as defined in Article 8 (9VAC5-80-1700 et seq.) and Article 9 (9VAC5-80-2000 et seq.) ofPart II of9VAC5 Chapter 80, were caaried out after December 31, 1970; or b. Coal-fired steam electric generating units subject to the provisions of §118 of the federal Clean Air Act, which commenced operation before July 1, 1957, and
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whose stacks were constructed under a construction 

### contract awardedbeforeFebruaxy 8, 1974. 3. Prior to the adoption of a new or revised emission limitation that is based on a good engineering practice stack heightthat exceeds the height allowedby subdivision 1 or 2 ofthe GEP definition, the board shall notify the public ofthe availability ofthe demonstration study and 

### shallprovidethe opportunityforpublic hearing on it. 4. For purposes of this subsection, such height shall not exceedtheheight allowedby subdivision 1 or2 ofthe GEP definition unlessthe ownerdemonstrates tothe satisfaction of the board, after 30 days notice to the public and opportunity for public hearing, that a greater height is necessaly as provided under subdivision 3 of the GEP definition. 5. In no event may the board prohibit any increase in any stack height orrestrict in any manner the maximum stack height ofany source. 6. Compliance with emission standards in this chaptershall not be affected in any manner by the stack height ofany source orany otherdispersion technique. J. Forthe purpose ofsubmitting compliance certifications or establishing whether or not a person has violated or is in violation of any standard in this chapter, nothing in this chapter shall preclude the use, including the exclusive use, of any credible evidence or infonnation, relevant to whether a source would have been in compliance with applicable requirements ifthe appropriate emission orcompliance test or procedurehadbeenperformed. 9VACS-50-20. Compliance.
A. Sixty days after achieving the maximum production rate, but not later than 180 days after initial startup, no owner or other person shall operate any new or modified source in violation of any standard ofperformance prescribed under this chapter. 1. Compliance with standards in this chapter, other than opacity standards, shall be determined by performance tests established by 9VAC5-50-30, unless specified otherwiseinthe applicable standard. 2. Compliance with federal requirements in this chapter may be determined by alternative or equivalent methods only ifapproved by the administrator. Forpurposes ofthis subsection, federal requirements consist ofthe following:

a New source performance standards established pursuantto §111 ofthe federal Clean AirAct. b. Allterms and conditions in afederal operating permit, including any provisions that limit a source’s potential to emit, unless expressly designated as not federally enforceable. c. Limitations and conditions that are part of an implementationplan. d. Limitations and conditions that are part of a section 111(d) or section 111(d)/129plan.

e. Limitations and conditions that are part of a federal construction permit issued under 40 CFR 52.21 or any constructionpermitissuedunderregulations approvedby EPA in accordancewith 40 CFR Part 51. f. Limitations and conditions that are part ofan operating permit issued pursuant to a program approved by EPA into an implementation plan as meeting EPA’s minimum criteria for federal enforceability, including adequate notice and opportunity for EPA and public comment prior to issuance of the final permit and practicable enforceability. 3. Compliance with opacity standards in this chapter shall gg be determined by conducting one or more of the following means:

a Conducting observations in accordancewithReference Method 9 or any alternative method approvedby EPA. if specified in the permit granted pursuant to 9VAC5 Chapter 80 (9VACS-80). For purposes of determining initial compliance, the minimum total time of observations shall be three hours (30 six-minute averages) for the performance test or other set of observations (meaning those fugitive-type emission
sources subject only to an opacity standard). Opacity readings ofportions ofplumes which contain condensed, uncombined water vapor shall not be used forpurposes ofdetermining compliance with opacity standards. b. Evaluation of data resulting from use of continuous monitoring by transmissometer, provided the instrument used meets Performance Specification 1 in Appendix B of40 CFRPart 60 andhas beenproperly maintained and thattheresulting datahavenotbeen altered in any way.

c. Use ofany othermethod approvedby EPA. 4. The opacity standards prescribedunderthis chapter shall apply at all times except during periods of startup, shutdown, malfunction and as otherwise provided in the applicable standard. 5. Variation from a specified standard may be granted by the boardfor adefiniteperiodfortesting and adjustment. B. No owner of a new or modified source subject to the provisions ofthis chapter shall fail to conduct performance tests asrequiredunderthis chapter.

C. No owner of a new or modified source subject to the provisions of this chapter shall fail to install, calibrate, maintain and operate equipment for continuously monitoring and recording emissions or process parameters or both as requiredunderthis chapter.

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D. No owner of a new or modified source subject to the provisions ofthis chapter shall fail to provide notifications and reports, revise reports, maintain records or report perfonnance test or monitoring results as required under this chapter.
E. At all times, including periods ofstartup, shutdown, soot blowing and malfunction, owners shall, to the extent practicable,. maintain and operate any affected facility including associated air pollution control equipment in a manner consistent with air pollution control practices for minimizing emissions. Determination ofwhether acceptable operating and maintenance procedures are being used will be based on information available to the board, which may include, but is not limited to, monitoring results, opacity observations, review of operating and maintenance procedures, and inspection ofthe source.

F. At all times the disposal ofvolatile organic compounds shall be accomplished by taking measures, to the extent practicable, consistent with airpollution control practices for minimizing emissions. Volatile organic compounds shall not be intentionally spilled, discarded in sewers which are not connectedto atreatmentplant, or stored in open containers or handled in any other mannerthatwouldresult in evaporation beyond that consistentwith air pollution control practices for minimizing emissions.

G. The following provisions apply with respect to compliancewith opacity standards.

1. For the purpose of demonstrating initial compliance, opacity observations shall be conducted concurrently with the initial performance test unless one of the following conditions apply.

a. If no performance test is required, then opacity observations shall be conducted within 60 days after achieving the maximum production rate at which the affected facility will be operated but no later than 180 days afterinitial startup ofthe facility. b. If visibility or other conditions prevent the opacity observations from being conducted concurrently with the initial performance test, the owner shall reschedule the opacity observations as soon after the initialperformance test as possible, but not laterthan 30 days thereafter, and shall advise the board ofthe rescheduled date. In these cases, the 30-day priornotification to the board required by 9VAC5-50-50 A 6 shall be waived. The rescheduled opacity observations shall be conducted (to the extent possible) under the same operating conditions that existed during the initial perfonnance test. The visible emissions observer shall determine whether visibility or other conditions prevent the opacity observations from being made concurrently with the initial performance test in accordance with procedures contained in Reference Method9. Opacity readings of portions of plumes which contain condensed, uncombined water vapor shall not be used for purposes of determining compliance with 

### opacity standards. The owner of an affected facility shall make available, upon request by the board, such records as may be necessaiy to determine the conditions under which the visual observations were made and shall provide evidence indicating proof of cun-ent visible observer emission certification. The results of continuous monitoring by transmissometerwhich indicate thatthe opacity at the time visual observations were made was not in excess ofthe standard are probative but not conclusive evidence ofthe actual opacity ofan emission, provided the source meets the burden ofproving that the instrument used meets (at the time of the alleged violation) Performance Specification 1 in Appendix B of40 CFR Part 60 andhas been properly maintained and (at the time ofthe alleged violation) that the resulting data have not been altered in any way. 2. Except as provided in subdivision 3 ofthis subsection, the owner of an affected facility to which an opacity standard in this chapter applies shall conduct opacity observations in accordance with subdivision A 3 of this section, shall record the opacity of emissions, and shall reportto theboardthe opacity results along with the results ofthe initial performance test. The inability ofan ownerto secure avisible emissions observer shall not be considered
a reason for not conducting the opacity observations concurrentwith the initial performance test. 3. The owner of an affected facility to which an opacity standard in this chapter applies may request the board to determine and to recordthe opacity ofemissions from the affected facility during the 

### initial performance test and at such times as may be required. The owner ofthe affected facility shall report the opacity results. Any request to the board to determine and to record the opacity ofemissions from an affected facility shall be included in the notification required in 9VAC5-50-50 A 6. If, for some reason, the board cannot determine andrecord the opacity of emissions from the affected facility during the performance test, then the provisions ofsubdivision 1 of this subsection shall apply. 4. An owner of an affected facility using a continuous opacity monitor (transmissometer) shall record the monitoring data produced during the initial performance test and shall furnish the board a written report of the monitoring results along with the Reference Method 9 and initialperformance testresults.
R The following provisions apply with respect to stack heights.

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# Regu!ations

1. The degree ofemission limitationrequired ofany source ownerforcontrol ofany air

### pollutant shall not be affected in any mannerby:

a. So much ofthe stack height ofany source as 

### exceeds good engineeringpractice; or b. Any other dispersiontechnique. 2. The provisions ofsubdivision 1 ofthis subsection shall notapply to:

a. Stack heights in existence, or dispersion techniques implemented on or before December 31, 1970, except where pollutants are being emitted from such stacks or using such dispersion techniques by sources, as defined in §111(a)(3) ofthe federal Clean Air Act, which were constructed, or reconstructed, or for which major modifications, as defined in Article 8 (9VAC5-80-1700 et seq.) aid Article 9 (9VAC5-80-2000 et seq.) ofPartII of9VAC5 Chapter 80, were carried out after December 31, 1970; or b. Coal-fired steam electric generating units subject to the provisions of §118 of the federal Clean Air Act, which commenced operation before July 1, 1957, and whose stacks were constructed under a construction contract awardedbeforeFebruary 8, 1974. 3. Prior to the adoption of a new or revised emission limitation that is based on a good engineering practice stackheightthat exceedstheheight allowedby subdivision 1 or 2 of the GEP definition, the board shall notify the public ofthe availability ofthe demonstration study and shallprovide opportunityforpublichearing on it. 4. For purposes of this subsection, such height shall not exceedtheheight allowedby subdivision 1 or2 ofthe GEP definition unless the ownerdemonstrates to the satisfaction of the board, after 30 days notice to the public and opportunity for public hearing, that a greater 

### height is necessary as provided under subdivision 3 of the GEP definition. 5. In no event may the board prohibit any increase in any stack height orrestrict in any manner the maximum stack 

### height ofany source. 6. Compliance with standards of perfonnance in this chapter shaH not be affected in any manner by the stack height ofany sourceor any other dispersion technique. I. Forthe purpose ofsubmitting compliance certifications or establishing whether or not a person has violated or is in violation of any standard 

### in this chapter, nothing in this chapter shallpreclude the use, including the exclusive use, of any credible evidence or information, relevant to whether a source would have been in compliance with applicable requirements ifthe appropriate performance or compliance test orprocedure hadbeen performed.

Volume 24, issue 5 Virginia RegisterofRegulations November 12, 2007 572 VA.R Dcc. No RO8-599: Filed October23. 2007, 123Sp.m.