A. Grab samples must be used for pH, cyanide, total phenols, oil and grease, sulfide, and volatile organic compounds. For all other pollutants, twenty four (24) hour composite samples must be obtained through flow proportional composite sampling techniques, unless time proportional composite sampling or grab sampling is authorized by the city, the samples must be representative of the discharge and the decision to allow the alternative sampling must be documented in the industrial user file for that facility or facilities. Using protocols (including appropriate preservation) specified in 40 CFR part 136 and appropriate EPA guidance, multiple grab samples collected during the twenty four (24) hour period may be composited prior to the analysis as follows: for cyanide, total phenols, and sulfides the samples may be composited in the laboratory. Composite samples for other parameters unaffected by compositing procedures as documented in approved EPA methodologies may be authorized by the city, as appropriate.
B. For sampling required in support of baseline monitoring and ninety (90) day compliance reports, a minimum of four (4) grab samples must be used for pH, cyanide, total phenols, oil and grease, sulfide and volatile organic compounds for facilities for which historical sampling data do not exist; for facilities for which historical sampling data are available, the city may authorize a lower minimum. For the reports by 40 CFR 403.12(e) and (h), the city will require the number of grab samples necessary to assess and assure compliance by industrial users with applicable pretreatment standards and requirements.
C. Samples should be taken immediately downstream from pretreatment facilities if such exist or immediately downstream from the regulated or manufacturing process if no pretreatment exists or as determined by the city and contained in the user's wastewater discharge permit. For categorical users, if other wastewaters are mixed with the regulated wastewater prior to pretreatment the user should measure the flows and concentrations necessary to allow use of the combined waste stream formula of 40 CFR 403.6(e) in order to evaluate compliance with the applicable categorical pretreatment standards. For other SIUs, for which the city has adjusted its local limits to factor out dilution flows, the user should measure the flows and concentrations necessary to evaluate compliance with the adjusted pretreatment standard(s).
D. All sample results must indicate the time, date and place of sampling, and methods of analysis, and certify that such sampling and analysis is representative of normal work cycles and expected pollutant discharges from the user. If a user is sampled more frequently than what was required in its wastewater discharge permit, it must submit all results of sampling and analysis of the discharge as part of its self-monitoring report. (Ord. 3374 §2, 2010)