1. (a) A facility must use a flow equalization basin if:

   1. (1) A facility's total daily influent flow volume occurs during a period of time less than or equal to ten hours of a day for any day of any week;
   2. (2) A facility experiences periods of time when it receives an influent flow of less than 10% of its design capacity for a period of time equal to or greater than 48 hours in any one week; or
   3. (3) At any time that flow equalization is necessary to minimize random or cyclic peaking of organic or hydraulic loadings.
2. (b) A flow equalization basin must have an upstream screening device.
3. (c) A flow equalization basin must include an aeration system sized to maintain a dissolved oxygen level of at least 1.0 milligram per liter (mg/l) in the flow equalization basin.
4. (d) A flow equalization basin must include a mixing system sufficient to prevent solids from settling.
5. (e) The size of a flow equalization basin must be based on diurnal flow variations and the size and capacity of downstream process units. The report must include the calculations justifying the size of a flow equalization basin.
6. (f) For pumped flow to an equalization basin, the effluent from a basin must be controlled by a flow-regulating device capable of maintaining a flow rate that allows downstream process units to operate properly.
7. (g) For pumped flow from an equalization basin, a variable-speed pump or multiple pumps are required to deliver a constant flow to downstream processing units.

Source Note:The provisions of this §217.128 adopted to be effective August 28, 2008, 33 TexReg 6843.