The use of a water level recorder should be used for head measurements. Consideration should be given to the fact that wastewater flow is subject to variation depending on season, day of the week and plant production levels. Collection of samples of wastewater for laboratory analysis requires extreme care to obtain a representative sample. A series of samples must be collected and composited in proportion to flow rates over a 24-hour period to obtain a representative sample for laboratory analysis. Where a plant has more than one sewer outlet, samples must be collected at each outlet and composited in proportion to the flow rate at the outlet. The composite for the entire plant is computed from these data. Flow is usually measured over a 24-hour period. To measure slugs, readings at 15-minute intervals are necessary. A continuous analyzer requires samples be taken every 15 minutes.
(Ord. 78-4, passed 2-13-1978; Ord. 92-20, passed 9-28-1992)