ON DECEMBER 13, 1994, TERRA INDUSTRIES' PORT NEAL FACILITY IN SIOUX CITY, IOWA EXPLODED, KILLING FOUR INDIVIDUALS, INJURING 18, AND CAUSING MASSIVE EVACUATIONS AND ENVIRONMENTAL DAMAGE. REGION VII CONDUCTED EMERGENCY RESPONSE ACTIVITIES AND ONGOING INVESTIGATIONS TO DETERMINE THE CAUSE OF THE EXPLOSION, AND TO ASSESS WHETHER THERE REMAINED A THREAT OF RELEASE. THE REFERRAL SETS FORTH CAA 112(R) GENERAL DUTY VIOLATIONS AND SEEKS CERCLA COST RECOVERY FOR THE RESPONSE ACTION.