§ 51.060  GRAB AND COMPOSITE SAMPLE COLLECTION.
   (A)   All wastewater samples must be representative of the user’s discharge.  Wastewater monitoring and flow measurement facilities shall be properly operated, kept clean, and maintained in good working order at all times.  The failure of a user to keep its monitoring facility in good working order shall not be grounds for the user to claim that sample results are unrepresentative of its discharge.
   (B)   Grab samples must be used for pH, cyanide, total phenols, oil and grease, sulfide, volatile organic compounds, and any other pollutants as required by 40 CFR 136. The POTW shall determine the number of grabs necessary to be representative of the user’s discharge.  See 40 CFR 403.12(g)(5) for additional grab sample number requirements for BMR and 90-day compliance reports.  Additionally, the POTW Director may allow collection of multiple grabs during a 24-hour period which are composited prior to analysis as allowed under 40 CFR 136.
   (C)   Composite samples: All wastewater composite samples shall be collected with a minimum of hourly aliquots or grabs for each hour that there is a discharge.  All wastewater composite samples shall be collected using flow proportional composite collection techniques, unless time-proportional composite sampling or grab sampling is authorized by the POTW Director. When authorizing time-proportional composites or grabs, the samples must be representative and the decision to allow the alternative sampling must be documented.
(Ord. passed 12-4-06; Am. Ord. passed 5-4-09; Am. Ord. passed 2-4-13)