Q762. Are subpart N reporters able to use a default assumption of 1.0 in Equation N-1 for determining calcination fraction of carbonate-based raw materials charged to glass melting furnaces?  How does this impact monitoring?

A762. The rule allows flexibility for reporters to use either (a) the default assumption of 1.0 or (b) methods that use measured data, such us undertaking chemical analysis to determine calcinations and mass fractions, using an x-ray fluorescence test, or other enhanced testing method published by an industry consensus standards organization (e.g., ASTM, ASME, API, etc.) to determine the calcination fraction (Fi) of each carbonate-based raw material charged to glass melting furnaces [98.143(b)(1)(iv),98.146(b)(6)]. If the reporter opts to use the default value of 1.0, then a chemical analysis does not have to be completed for that reporting year.

This is consistent with EPA’s intent in the response to comments to the final rule, published 10/30/2009 [74 FR 56260]. See Section 5, Other Subpart N comments (see p. 4 within this document): http://www2.epa.gov/sites/production/files/2015-02/documents/subpartn-rtc-glassproduction.pdf.

Further, within Subpart N, this guidance is consistent with similar flexibility to use an analysis or a default assumption for determining the mass fraction of carbonates charged to glass melting furnaces under 98.143(c).