SECTION 252:656-13-3. Diurnal flow equalization  


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  • (a)   General. Provide flow equalization basins to equalize variations in organic and hydraulic loadings where large diurnal organic or hydraulic variations of organic or hydraulic loading are expected, where peak to average is greater than 2:1. Wet weather (excess flow) basins are covered in 252:656-13-4.
    (b)   Location. Locate basins downstream of pretreatment facilities such as bar screens and grit chambers.
    (c)   Size. Capacity must be sufficient to reduce expected flow and load variations to less than or equal to 2:1. The volume required to achieve the desired degree of equalization can be determined from a cumulative flow plot over a representative 24-hour period.
    (d)   Operation.
    (1)   Mixing. Provide airor mechanical equipment to maintain adequate mixing. Design corner fillets and hopper bottoms with draw-offs to alleviate the accumulation of sludge and grit.
    (2)   Aeration. Aeration equipment shall be sufficient to maintain a minimum of 1.0 mg/l of dissolved oxygen in the basin at all times. Air supply rates shall be at least 1.25 cfm/1,000 gallons of storage capacity. Isolate the air supply from other treatment plant aeration requirements to facilitate process aeration control.
    (3)   Controls. Equip inlets and outlets for all basin compartments with flow control devices. Provide facilities to measure and indicate liquid levels and flow rates leaving the basin(s).
[Source: Added at 17 Ok Reg 1140, eff 6-1-00; Amended at 23 Ok Reg 937, eff 6-15-06; Added at 28 Ok Reg 1282, eff 7-1-11]