Alternating Flow Diversion

Because the alternating flow diversion system is intended to hold the total flow for a fixed time period (normally 24 hr), its design is based strictly on flow. Therefore, the design criteria depend on flow variability, standard deviation, and maximum flow for the time frame.

For example, an industrial facility has a total daily flow and pollution profile as shown in Table 7.13.1. If a thirty-day period is assumed to represent one month, the equalization basin can be designed using Table 7.13.1 and a management design criterion of 110% of maximum flow. Each of the equalization basins is designed to hold 686.98 m3. Therefore, the management design criterion (that is, 110% of maximum flow) becomes the dominant variable in this equation.

This variable is given to the design engineers by plant management or assumed to be based on prior experience. The following equation applies:


Vt = Volume of the equalization basin, m3 T = Time period of equalization Dc = Management design criteria, % Fc = Management flow criteria (fa, average flow for a time period, or fm, maximum flow for a time period), m3/hr k = Units conversion constant

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