Ill. Admin. Code tit. 35, § 310.311 Demonstration of Consistent Removal

• Library: Illinois Administrative Code
• Edition: 2023
• Currency: Current through Register Vol. 47, No. 52, December 29, 2023
• Citation: Ill. Admin. Code tit. 35, § 310.311
• Year: 2023

The Agency must authorize a POTW to grant a removal credit that does not exceed the POTW's consistent removal rate. To demonstrate consistent removal, the POTW must, for each pollutant with respect to which removal credit authorization is sought, collect influent and effluent data, and calculate consistent removal in accordance with the following requirements. As a condition of retaining removal credits authorization, the POTW's consistent removal must continue to be equal or greater than the removal credit.

a) Representative Data. Seasonal. The data must be representative of yearly and seasonal conditions to which the POTW is subjected for each pollutant for which a discharge limit revision is proposed.

b) Representative Data. Quality and quantity. The data must be representative of the quality and quantity of normal effluent and influent flow if such data can be obtained. If such data are unobtainable, alternate data or information may be presented for approval to demonstrate consistent removal.

c) Sampling Procedures

1) Composite. The influent and effluent operational data must be obtained through 24-hour flow-proportional composite samples. Sampling may be done manually or automatically, and discretely or continuously. For discrete sampling, at least 12 aliquots must be composited Discrete sampling may be flow-proportioned either by varying the time interval between each aliquot or the volume of each aliquot. All composites must be flow-proportional to either stream flow at time of collection of influent aliquot or to the total influent flow since the previous influent aliquot Volatile pollutant aliquots must be combined in the laboratory immediately before analysis.

2) Number of SamplesA) Twelve samples must be taken at approximately equal intervals throughout the full year. Sampling must be evenly distributed over the days of the week so as to include non-workdays. If the Agency determines that this schedule will not be most representative of the actual operation of the POTW treatment plant, the Agency must approve an alternative sampling schedule. B) Upon concurrence of the Agency, a POTW may utilize a historical database amassed during the three years immediately preceding the application if the data otherwise meet the requirements of this Section. For the historical database to be approved, it...