REFERRAL AGAINST APACHE NITROGEN PRODUCTS INCORPORATED FOR VIOLATIONS OF THE NSPS AT ITS TWO NITRIC ACID PLANTS AOP-3 AND AOP-4. VIOLATIONS HAVE BEEN ONGOING SINCE APPROX JULY 1999. ANP HAS EMITTED NITROGEN OXIDES (NOX) IN THE FORM OF NITROGEN OXIDE AND NITROGEN DIOXIDE. EMISSION HAS BEEN IN EXCESS OF THE LIMIT SET FORTH IN NSPS SUBPART G DURING PERIODS OF STARTUP AT PLANTS AOP-3 AND AOP-4. THESE EXCESS EMISSIONS VIOLATE THE OPERATION AND MAINTENANCE PROVISION AT 40 CFR 60.11(D), WHICH REQUIRES AN OWNER OR OPERATOR TO MAINTAIN AND OPERATE AN AFFECTED FACILITY IN A MANNER CONSISTENT WITH GOOD AIR POLLUTION CONTROL PRACTICE AT ALL TIMES, INCLUDING PERIODS OF STARTUP, SHUTDOWN, AND MALFUNCTION.