1. a) Number of Units

   Multiple units capable of independent operation are desirable and shall be provided in all plants where design average flows exceed 100,000 gallons per day. Plants not having multiple units shall include other provisions to assure continuity of treatment.

2. b) Arrangement

   Settling tanks shall be arranged in accordance with Sections 370.520(e) and 370.710(g).

3. c) Flow Distribution

   Effective flow splitting devices and control appurtenances shall be provided to insure proper organic and hydraulic proportion of flow to each unit. Refer to Section 370.520(f).

4. d) Tank Configuration

   Consideration should be given to the probable flow pattern in the selection of tank size and shape, and inlet and outlet type and location.

(Source: Amended at 21 Ill. Reg. 12444, effective August 28, 1997)