Section 41. Emission monitoring procedures for existing sources

A. The provisions of this section shall apply to existing sources. These provisions may also apply, at the discretion of the board, to new and modified sources if the source type is not subject to Article 5 (9VAC5-50-400 et seq.) of 9VAC5 Chapter 50.

B. General procedures.

1. Continuous monitoring system performance evaluations shall be conducted in accordance with the requirements and procedures contained in the applicable performance specification in Appendix B of 40 CFR Part 60 as follows:

a. Continuous monitoring systems for measuring opacity of emissions shall comply with performance specification 1.

b. Continuous monitoring systems for measuring nitrogen oxides emissions shall comply with performance specification 2.

c. Continuous monitoring systems for measuring sulfur dioxide emissions shall comply with performance specification 2.

d. Continuous monitoring systems for measuring oxygen content or carbon dioxide content of effluent gases shall comply with performance specification 3.

2. Owners of all continuous monitoring systems installed in accordance with the provisions of this section shall check the zero and span drift at least once daily in accordance with the method prescribed by the manufacturer of such systems unless the manufacturer recommends adjustments at shorter intervals, in which case such recommendations shall be followed. The zero and span shall, as a minimum, be adjusted whenever the 24-hour zero drift or 24-hour calibration drift limits of the applicable performance specifications in Appendix B of 40 CFR Part 60 are exceeded. For continuous monitoring systems measuring opacity of emissions, the optical surfaces exposed to the effluent gases shall be cleaned prior to performing the zero or span drift adjustment except that for systems using automatic zero adjustments, the optical surfaces shall be cleaned when the cumulative automatic zero compensation exceeds 4% opacity. Unless otherwise approved by the board, the following procedures, as applicable, shall be followed:

a. For extractive continuous monitoring systems measuring gases, minimum procedures shall include introducing applicable zero and span gas mixtures into the measurement system as near the probe as is practical. Span and zero gases certified by their manufacturer to be traceable to National Bureau of Standards reference gases shall be used whenever these reference gases are available. The span and zero gas mixtures shall be the same composition as specified in Appendix B of 40 CFR Part 60. Every six months from date of manufacturer, span and zero gases shall be reanalyzed by conducting triplicate analyses with Reference Methods 6 for SO₂, 7 for NO_X, and 3 for O₂ and CO₂, respectively. The gases may be analyzed at less frequent intervals if longer shelf lives are guaranteed by the manufacturer.

b. For nonextractive continuous monitoring systems measuring gases, minimum procedures shall include upscale checks using a certified calibration gas cell or test cell which is functionally equivalent to a known gas concentration. The zero check may be performed by computing the zero value from upscale measurements or by mechanically producing zero condition.

c. For continuous monitoring systems measuring opacity of emissions, minimum procedures shall include a method for producing a simulated zero opacity condition and an upscale (span) opacity condition using a certified neutral density filter or other related technique to produce a known obscuration of the light beam. Such procedures shall provide a system check of the analyzer internal optical surfaces and all electronic circuitry including the lamp and photodetector assembly.

3. Except for system breakdowns, repairs, calibration checks, and zero and span adjustments required under subdivision B 2 of this section, all continuous monitoring systems shall be in continuous operation and shall meet minimum frequency of operation requirements as follows:

a. All continuous monitoring systems for measuring opacity of emissions shall complete a minimum of one cycle of sampling and analyzing for each successive 15-second period and one cycle of data recording for each successive six-minute period.

b. All continuous monitoring systems for measuring nitrogen oxides, sulfur dioxide, carbon dioxide or oxygen shall complete a minimum of one cycle of operation (sampling, analyzing and data recording) for each successive 15-minute period.

4. All continuous monitoring systems or monitoring devices shall be installed such that representative measurements of emissions or process parameters from the affected facility are obtained. Additional procedures for location of continuous monitoring systems contained in the applicable performance specifications in Appendix B of 40 CFR Part 60 shall be used.

5. When the effluents from a single affected facility or two or more affected facilities subject to the same standards are combined before being released to the atmosphere, the owner may install applicable continuous monitoring systems on each effluent or on the combined effluent. When the affected facilities are not subject to the same standards, separate continuous monitoring systems shall be installed on each effluent. When the effluent from one affected facility is released to the atmosphere through more than one point, the owner shall install applicable continuous monitoring systems on each separate effluent unless the installation of fewer systems is approved by the board.

6. Owners of all continuous monitoring systems for measurement of opacity shall reduce all data to six-minute averages for six-minute periods and for systems other than opacity to one-hour averages for one-hour periods. Six-minute opacity averages shall be calculated from 24 or more data points spaced at approximately equal intervals over each six-minute period. For systems other than opacity, one-hour averages shall be computed from four or more date points spaced at approximately equal intervals over each one-hour period. Data recorded during periods of system breakdowns, repairs, calibration checks and zero and span adjustments shall not be included in the data averages computed under this subdivision. An arithmetic or integrated average of all data may be used. The data output of all continuous monitoring systems may be recorded in reduced or nonreduced form (e.g., ppm pollutant and percent O₂ of lb or pollutant per million Btu). All excess emissions should be converted into units of the standard using the applicable conversion procedures specified in the applicable standard. After conversion into units of the standard, the data may be rounded to the same number of significant digits used to specify the applicable standard (e.g., rounded to the nearest one percent opacity).

C. Specific procedures. Specific procedures for emission monitoring may be found in the rule covering the source type in question.

Historical Notes

Derived from Volume 13, Issue 18, eff. July 1, 1997.

Statutory Authority

§ 10.1-1308 of the Code of Virginia.