"Bullseye's claim to operating periodic furnaces is contradicted by annual reports to DEQ required by its discharge permit. From 2000 to 2003, the reports state: 'Furnaces operate 24 hours a day; they are either 'melting' at 100% firing capacity, or they are 'idling' at 45% firing capacity.'"

This supports the claim that the furnaces are only melting glass "periodically," while operating in idle mode (45% firing rate) the rest of the time. If no glass is being melted, there can be no HAPs emissions (except from the combustion process). So they really did not lie when they said they use their furnaces periodically. Thus the EPA approved the exemption (though this may have been a bad decision without having actual emissions data).

A little too parsed there my friend. They are relying on a 'technical' term for batch vs continuous process. ALL furnaces shut down periodically for service. The designation has more to do with the mechanisms and processes used to feed batch to the furnace and remove molten glass than it does how long or often it's heating at what temperature....