Sample collection. Samples for oil and grease, temperature, pH, cyanide,
phenols, toxicity, sulfides, and volatile organic chemicals must be
obtained using grab collection techniques. All other wastewater samples
shall be collected using flow proportional composite sampling procedures.
In the event flow proportional sampling is infeasible, the Supervisor
may authorize the use of time proportional sampling, or a minimum
of four grab samples where the user demonstrates that this will provide
a representative sample of the effluent being discharged. In addition,
grab samples may be required to show compliance with instantaneous
discharge limits.