Whenever a user is required to collect samples for analysis, the requirements listed below shall be followed.
A minimum of four (4) grab samples within a twenty-four (24) hour period must be used for pH, cyanide, total phenols, sulfide and volatile organics. For oil and grease, one (1) grab sample during normal operations of the facility will be sufficient. The City will determine on a case-by-case basis whether the user will be able to composite the individual grab samples. For all other pollutants, twenty-four (24) hour composite samples must be obtained through flow-proportional composite sampling techniques where feasible. The City may waive flow-proportional composite sampling for any user that demonstrates, to the satisfaction of the City, that flow-proportional sampling is not feasible. In such cases, samples may be obtained through time-proportional composite sampling techniques or through a minimum of four (4) grab samples where the user demonstrates that this will provide a representative sample of the effluent being discharged.
For nonsignificant users, samples should be taken immediately downstream from a point where any, and all, industrial waste streams from the facility are combined, or at a point determined by the City and/or contained in a special agreement.
All sample results shall indicate the time, date and location of sampling. They shall also include methods of analyses. All sampling and analyses shall be representative of normal work cycle and expected pollutant discharges from the user.