Читать книгу Continuous Emission Monitoring - James A. Jahnke - Страница 65

The most obvious impact of continuous data is that more information is available to environmental control agencies. By obtaining such data (or summaries of data), fewer on‐site inspections and manual reference method tests may be necessary to enforce emissions standards. Different approaches can be taken by an agency in applying CEM data to meet its goals of maintaining and improving air quality. Properly used, CEM data can expand an agency's enforcement capabilities. The CEM database can assist in negotiating the installation of control equipment or requiring process modifications, or the data can provide the basis for a supply‐and‐demand market‐based approach for improving air quality.

One would expect the regulatory application of CEM system data to be straightforward. If a source has a regulated pollutant emission limit and a monitoring system is installed to monitor the pollutant emissions, then it should be possible to determine at any time whether the source is emitting either under or over that limit. A source is said to be out of compliance if it exceeds its regulated emissions limits. A source is in compliance with emission standards if the emissions are under those limits. CEM systems do this and, by definition, provide emissions data on a continuous basis.

However, the use of monitoring data by air pollution control agencies with regard to enforcement issues becomes somewhat complicated. Technically, a continuous compliance determination method means:

a method specified by an applicable standard or an applicable permit condition which: (1) is used to determine compliance with an emission limitation or standard on a continuous basis, consistent with the averaging period established for the emission limitation or standard; and (2) provides data either in units of the standard or correlated directly with the compliance limit. (U.S. EPA 1997b)

Averaging periods, units, and the degree of correlation with the compliance limit all become issues in the application of monitoring systems to enforcement programs. These issues are readily resolved with the application of CEM systems, but resolution becomes more difficult when predictive emission monitoring systems (PEMS), continuous parameter monitoring systems (CPMS), or other such correlation methods are used. Problems can also arise from other areas. Arguments have been made that emission limits were established based upon EPA test (reference) methods such as those given in 40 CFR 60 Appendix A. Since a CEM system is not an EPA reference method, it has been argued that CEM system data cannot be used in enforcement cases. Also, early experience with CEM systems was somewhat less than satisfactory, and the lack of QA programs often made the CEM data less defensible in court. The conservative approach was to rely ultimately on the reference methods for enforcement issues.

The use of CEM system data for enforcement has grown as confidence has increased in the quality of the data. Specifying in a permit that a CEM system is the compliance method also helps to eliminate any ambiguity regarding compliance determinations. The EPA programs developed in response to the volume of data available have matured from the use of CEM systems from compliance indicating systems to compliance monitoring systems.

Compliance assurance monitoring (CAM) programs, the credible evidence rule, and periodic monitoring requirements for State Title V CAAA permits are also relevant to predictive and parameter monitoring methods, and fill in the monitoring gaps where CEM systems are not explicitly required (although CEM systems may still be used in such circumstances). As a result, EPA has put in place a regulatory framework that can be used to determine if a source is meeting its emission limits and standards at all times, as is required by the Clean Air Act of 1990.