Q310. For subpart AA in e-GGRT, on the screen to enter CO2 emissions from makeup chemicals, why are there two boxes to check?

A310. In accordance with the procedures for missing data for subpart AA (section 98.275), owners or operators are required to keep records of the procedures used to account for missing data. Checkboxes are provided in e-GGRT to give the user the opportunity to indicate if a substitute value was used for the annual quantity of CaCO3 and Na2CO3 to calculate the CO2 emissions from makeup chemicals. Similarly, other subpart AA screens provide checkboxes to indicate if substitute values were used for the mass of spent liquor solids used to calculate biogenic CO2 emissions and emissions of CH4 or N2O from spent liquor solids combustion using equations AA-1 and AA-2.