Opinion ID: 768833
Heading Depth: 4
Heading Rank: 2

Heading: Emissions Multiplier for Low Mass Emission Units

Text: 142 PP&L also contends that EPA arbitrarily required low mass emission units(LMEUs) to use a 15% multiplier to calculate their emissions. We disagree. 143 EPA allows LMEUs either to use a generic default NOx or to determine a unit-specific NOx emission rate by conducting a stack test once every five years. Because EPA found that the stack test results can vary by 15% or more depending on atmospheric conditions, EPA requires an LMEU to calculate its emissions rate by adding 15% to the stack test result. See Final Rule, 63 Fed. Reg. at 57,490. 144 PP&L contends that this is unreasonable because EPA has stated that the testing would likely underestimate emissions during cooler less humid conditions. See id. PP&L reasons that because the SIP call applies only during summer seasons (when ozone forms), that the stack test underestimates emissions during the winter cannot justify the 15% multiplier. This contention is to no avail. Because the record contains evidence that NOx rates determined by the stack test can vary widely even during the ozone season, EPA's decision was reasonable. See Docket A-97-35, Item IV-A-1 at 43-54 (August 26, 1998).