Monitoring Locations and Frequency
Permits specify exactly where samples are taken and how often — frequency and location drive both the analytical budget and the compliance data you generate.
Monitoring location is identified in the permit (typically as Outfall 001 for the main effluent discharge, with additional outfalls for combined sewer overflows or alternate discharge routes).
Sample frequency (daily, weekly, monthly) determines both your analytical budget and how much compliance data you generate. Many limits become weekly or daily at higher flow categories.
Sample type (grab, 24-hour composite, 8-hour composite) is specified per parameter and reflects what the parameter requires — grab for pH, 24-hour composite for BOD, etc.
If monitoring location or frequency deviates from the permit — even consistently for years — it can create compliance problems at permit renewal. Document the rationale for any deviation and request a formal permit modification.
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