Virginia Administrative Code
Title 9 - ENVIRONMENT
Agency 5 - STATE AIR POLLUTION CONTROL BOARD
Chapter 40 - EXISTING STATIONARY SOURCES
Part I - Special Provisions
Section 9VAC5-40-41 - Emission monitoring procedures for existing sources

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:

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:

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:

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).