WEST CHICAGO IU THE POLLUTANT IS A MASS BASED PERMIT UNDER METAL MOLDING AND CASTING 40 C.F.R. 464. CATEGORICAL AND LOCAL PRETREATMENT VIOLATIONS EFFECTIVE IMMEDIATELY, ALCOA SHALL COMMENCE MONITORING ITS WASTEWATER DISCHARGE (S) ON WEEKLY BASIS FOR THE FOLLOWING PARAMETER: CR, CR+6, ZN AND O & G. EACH WEEKLY ANALYSIS SHALL PROVIDE ALL DATA NECESSARY TO DETERMINE COMPLIANCE WITH ALL APPLICABLE PRETREATMENT STANDARDS. THE DATA SHALL BE SUMMARIZED AND SUBMITTED IN QUARTERLY REPORTS TO U.S. EPA DUE APRIL 30, JULY 31, OCTOBER 31, AND JANUARY 31. THIS WEEKLY MONITORING SHALL CONTINUE UNTIL SUCH TIME AS DIRECTED OTHERWISE BY WRITTEN NOTIFICATION. THIS DATA MUST BE INDEPENDENT OF DATA GATHERED BY THE POTW. SAMPLING AND ANAYLIS SHALL BE PERFORMED IN ACCORDANCE WITH 40 C.F.R. PART 136 AND 403.12(G), AND AMMENDMENTS THERETO, UNLESS AN ALTERNATIVE PROCEDURE OR METHOD IS APPROVED BY THE REGIONAL ADMINISTRATOR. SAMPLING FOR CR, CR+6 AND ZN SHALL BE CONDUCTED BY 24-HOUR COMPOSITE SAMPLING, AND SAMPLING FOR O & G SHALL BE CONDUCTED BY INSTANTANEOUS GRAB SAMPLE.