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, based on data that is representative of conditions occurring during the reporting period.
(A) Except as indicated in divisions (B) and (C)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 the Superintendent. Where time-proportional composite sampling or grab sampling is authorized by the city, 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 the city, as appropriate. In addition, grab samples may be required to show compliance with instantaneous limits.
(B) Samples for oil and grease, temperature, pH, cyanide, total phenols, sulfides, and volatile organic compounds must be obtained using grab collection techniques.
(1) Where samples are collected for a pollutant listed in this division (B) having a daily maximum limit established under § 55.019:
(a) A minimum of four time-proportional grab samples shall be collected for each 24-hour period during which wastewater monitoring is performed.
(b) Each time-proportional grab sample shall be analyzed separately and the results of all analyses for samples collected during the same 24-hour period shall be averaged to determine compliance; or such samples shall be composited as required by the approved analytical method prior to analysis.
(2) Where samples are collected for a pollutant listed in this division (B) having an instantaneous maximum limit established under § 55.019; the results of analysis for individual grab samples shall be compared to the applicable instantaneous maximum limit to determine compliance or establish noncompliance.
(C) For sampling required in support of baseline monitoring and 90-day compliance reports required in §§ 55.190 and 55.192 [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, the Superintendent may authorize a lower minimum. For the reports required by § 55.193 [40 CFR 403.12(e) and 403.12(h)], the non-residential user is required to collect the number of grab samples necessary to assess and assure compliance by with applicable pretreatment standards and requirements.
(D) For sampling required to determine compliance with an applicable categorical discharge standard, samples should be taken immediately downstream from pretreatment facilities if such exist or immediately downstream from the regulated process if no pretreatment exists. 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 wastestream formula in 40 CFR 403.6(e) to evaluate compliance with the pretreatment standards. Where an alternate concentration or mass limit has been calculated in accordance with 40 CFR 403.6(e) this adjusted limit along with supporting data shall be submitted to the control authority.
(Ord. 6619, passed 1-28-13)