C. Other Measures Considered
The following strategies were also considered as being potential emission reduction measures available for the asphalt roofing manufacturing source category, but were not evaluated as a new emission reduction strategy.
• Emission standards (for PAH and formaldehyde) – lower applicability thresholds to include smaller sources. This strategy was not evaluated because the area source NESHAP for this source category does not contain applicability thresholds. Therefore, asphalt roofing manufacturing sources that are not subject to the major source NESHAP (40 CRF Part 63, subpart LLLLL) are subject to the area source NESHAP (40 CFR Part 63, subpart AAAAAAA) and were to be in compliance with these standards by December 2, 2010. As pointed out above, the three sources identified in the PATS area are subject to the area source NESHAP for asphalt roofing manufacturing.
• Reduce use – review asphalt use and its applications. This strategy is not only a pollutant prevention technique, but also a cost savings measure. In fact, U.S. EPA has acknowledged that market-driven process changes have already accounted for significant asphalt reductions in the roofing manufacturing industry (Federal Register, 2009). These reductions have come from the change in industry from felt substrates to fiberglass mat substrates, which require less asphalt application. We would expect that facilities would continue to research techniques and practices to help reduce the amount of raw materials consumed in product manufacturing. However, we are unable to determine if any further improvements are possible at each facility, much less be able to quantify the potential emissions reductions that could be achieved and associated costs for the three facilities identified in the PATS area in this source category.
• Review the use of filters or thermal oxidizers on asphalt storage tanks as a means for emission reductions