§ 439.12 Effluent limitations attainable by the application of the best practicable control technology currently available (BPT).
Except as provided in 40 CFR 125.30 through 125.32, any existing point source subject to this subpart must achieve the following effluent limitations representing the application of BPT:
(a) The maximum monthly average limitation for BOD5, expressed as mass loading (lbs., kg) per day, must reflect not less than 90 percent reduction in the long-term average daily BOD5 load of the raw (untreated) process wastewater, multiplied by a variability factor of 3.0.
(1) The long-term average daily BOD5 load of the raw process wastewater (i.e., the base number to which the percent reduction is applied) is defined as the average daily BOD5 load during any calendar month, over 12 consecutive months within the most recent 36 months, and must include one or more periods during which production was at a maximum.