THIS REFERRAL IS REQUESTED FOR ALLEGED VIOLATIONS OF THE CLEAN AIR ACT AT CONOCO'S DENVER, CO REFINERY AND BILLINGS, MT. REFINERY. THIS IS PART OF THE NATIONAL PETROLEUM REFINERY INITIATIVE. REGION 8 HAS NOT CONDUCTED DETAILED INVESTIGATIONS OF POTENTIAL AIR VIOLATIONS AT ITS TWO CONOCO REFINERIES. THE INFORMATION CONTAINED IN THIS LETTER IS BASED PRIMARILY ON WHAT WE HAVE LEARNED AS NEGOTIATIONS TOOK PLACE THIS YEAR. REGION 8 HAS NOT CALCULATED PENALTIES FOR POTENTIAL CAA VIOLATIONS SINCE WE DID NOT UNDERTAKE AN INVESTIGATION OF SUCH VIOLATIONS. IF THE EXPECTED SETTLEMENT OF THESE CASES DOES NOT OCCUR, FURTHER CASE DEVELOPMENT WOULD BE REQUIRED BEFORE THE FILING OF THE COMPLAINTS.