Building Materials Manufacturing d/b/a GAF (GAF) failed to achieve 95% destruction efficiency of total hydrocarbons at a coalescing filter unit during a performance test in March 2015. GAF also exceeded a volatile organic carbon emission limit during the performance test in March 2015. This failed performance test violates conditions in their 2014 and 2015 Federally Enforceable State Operating Permits (FESOP). We discovered this violation through an inspection of the GAF facility on September 29, 2015. The inspection was performed in response to several odor complaints we received about the facility. On November 18, 2015, we issued GAF a Notice of Violation (NOV) for violations of their FESOP relating to this failed stack test. Since the issuance of the NOV, GAF has replaced their coalescing filter with a regenerative thermal oxidizer (RTO), equipped with a pre filter. On December 18, 2015, GAF conducted a performance test at the RTO. The results of this test confirmed compliance with their permit limits. This CAFO requires GAF to pay a penalty of $221,458 and resolves the NOV issued to GAF on November 18, 2015.