BFI OWNS AND OPERATES A MEDICAL WASTE INCINERATOR AT THE MARICOPA MEDICAL CENTER IN PHOENIX, ARIZONA, WHICH IS LOCATED WITHIN THE JURISDICTION OF THE DIVISION OF AIR POLLUTION CONTROL OF MARICOPA COUNTY ENVIRONMENTAL SERVICES DEPARTMENT. BFI LOADS MEDICAL WASTE INTO THE INCINERATOR'S PRIMARY CHAMBER, IN WHICH THE WASTE IS BURNED AT 1400 DEG. F AND REDUCED TO ASH. WHEN THE INCINERATOR WAS NOT OPERATING PROPERLY, THE WASTE MATERIAL SMOLDERED, RESULTING IN THE RELEASE OF EXCESS PARTICULATE MATTER TO THE ATMOSPHERE. THESE RELEASES CAUSED OPACITY PROBLEMS AT THE INCINERATOR. MARICOPA DAPC RULE 20 REQUIRES A PERSON TO OBTAIN AN INSTALLATION PERMIT FROM THE MARICOPA DAPA PRIOR TO ERECTING, INSTALLING, OR REPLACING EQUIPMENT THAT MAY AFFECT AIR POLLUTION. MARICOPA DAPC RULE 35 REGULATES THE USE OF INCINERATORS AND PROVIDES THAT NO PERSON SHALL EMIT INTO THE ATMOSPHERE FROM ANY INCINERATOR FOR AN AGGREGATE OF MORE THAN THIRTY SECONDS IN ANY SIXTY MINUTES, SMOKE THE APPEARANCE, DENSITY, OPACITY OR SHADE OF WHICH IS DARKER THAN 20 PERCENT OPACITY. RULES 20 AND 35 ARE PART OF THE FEDERALLY APPROVED AND FEDERALLY ENFORCEABLE STATE IMPLEMENTATION PLAN SUBMITTED TO EPA BY THE STATE OF ARIZONA PURSUANT TO SECTION 110 OF THE ACT. EPA HAS DETERMINED THAT BFI VIOLATED MARICOPA DAPC RULES 20 AND 35 BY REPEATEDLY EMITTING INCINERATOR EXHAUST GASES TO THE ATMOSPHERE THAT EXCEEDED 20 PER