Respondent owned and operated a refinery. On March 31-April3, 2014, EPA Region 6 conducted an unannounced, onsite CAA 40 C.F.R. Part 68 and Section 112(r) Partial Compliance Evaluation of the Facility. The refinery submitted a single RMP with covered processes that are subject to Program 3 requirements. The regulated flammable substances that are above the threshold quantities identified in 40 C.F.R. § 68.130 are:butene, propane, propylene, butane, isobutane, methane, hydrogen, flammable mixture (components are butane, isopentane, pentane, 1, 3 butadiene, propylene and ethyl mercaptan), and 1-pentene. The regulated toxic substances that are above the threshold quantities identified in 40 C.F.R. § 68.130 are hydrochloric acid and hydrogen sulfide.