CYPRUS VIOLATED SECTION 103(A) OF CERCLA. SECTION 103(A), IN RELEVANT PART, REQUIRES THAT FACILITIES IMMEDIATELY NOTIFY THE NATIONAL RESPONSE CENTER (NRC) OF ANY RELEASE OF A REPORTABLE QUANTITY OF A CERCLA HAZARDOUS SUBSTANCE. CYPRUS FAILED TO IMMEDIATELY NOTIFY THE NRC, AS REQUIRED BY CERCLA, AFTER A 110,000 POUND RELEASE OF SULFURIC ACID IN 1992. CYPRUS OPERATES A COPPER MINING OPERATION ON LEASED LAND WITHIN THE SIF OIDAK DISTRICT OF THE TOHONO O'ODHAM NATION, IN PINAL COUNTY, ARIZONA. ON SEPTEMBER 2, 1992, CYPRUS EMPLOYEES DISCOVERED THAT A CYPRUS PIPELINE HAD RUPTURED AND RELEASED SULFURIC ACID LEACHATE SOLUTION INTO A SMALL ARROYO (DRY WASH), SEVERELY DAMAGING THE SURROUNDING VEGETATION. CYPRUS REPAIRED THE PIPELINE AND DID NOT REPORT THE RELEASE TO ANY RESPONSE AUTHORITIES.