(A) Samples collected to satisfy reporting requirements must be based on data obtained through appropriate sampling and analysis performed during the period covered by the report and based on data that is representative of conditions occurring during the reporting period.
(B) Except as indicated in divisions (C) and (D) below, the user must collect wastewater samples using 24-hour flow-proportional composite sampling techniques, unless time-proportional composite sampling or grab sampling is authorized by CW. Where time-proportional composite sampling or grab sampling is authorized by CW, the samples must be representative of the discharge. Using protocols (including appropriate preservation) specified in 40 CFR Part 136 and appropriate EPA guidance, multiple grab samples collected during a 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 or in the field; for volatile organics and oil and grease, the samples may be composited in the laboratory. Composite samples for other parameters unaffected by the compositing procedures as documented in approved EPA methodologies may be authorized by CW, as appropriate. In addition, grab samples may be required to show compliance with instantaneous limits.
(C) Samples for oil and grease, temperature, pH, cyanide, total phenols, sulfides, and volatile organic compounds must be obtained using grab collection techniques.
(D) For sampling required in support of baseline monitoring and 90-day compliance reports required in §§ 50.085 and 50.087 (40 CFR 403.12(b) and (d)), a minimum of four 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, CW may authorize a lower minimum. For the reports required by § 50.088 (40 CFR 403.12(e) and 403.12(h)), the industrial user is required to collect the number of grab samples necessary to assess and assure compliance by with applicable pretreatment standards and requirements.
(Ord. 653, passed 11-15-21)