Respondent operates a petrochemical manufacturing facility (NAICS Code 32511) that produces vinyl chloride for use in the plastics industry. The production areas represent a single RMProgram covered process involving sixteen (16) RMProgram regulated chemicals. At its stationary source, the Respondent has 27,000,000 pounds of vinyl chloride and 6,700,000 pounds of chlorine. At its stationary source, the Respondent has one RMProgram level 3 covered process, which stores or otherwise uses regulated toxic and flammable substances in amounts exceeding applicable thresholds. The EPA began an investigation into releases of hazardous chemicals at the Respondent’s facility after EPA received a referral from the Commonwealth of Kentucky’s Department of Environmental Protection concerning a September 12, 2011, release of 11,000 pounds of vinyl chloride. In an CAA Section 114 letter dated March 15, 2016, EPA requested the Respondent to provide information on all chemical releases occurring after January 1, 2011, that the Respondent reported to the National Response Center, and/or to the State Emergency Response Commission and the Local Emergency Planning Committee. In its response, in addition to the September 12, 2011, vinyl chloride release, the Respondent provided information on reportable releases occurring on April 11, 2011; April 25, 2012; August 22, 2013; and June 20, 2014.