15.20.030 Federal Categorical Pretreatment Standards.
The national categorical pretreatment standards promulgated by EPA and found at 40 CFR Chapter I, Subchapter N, Parts 405 through 471 are incorporated into and are enforceable under this title. When a categorical pretreatment standard is expressed only in terms of pollutant concentrations, an industrial user may request that the City convert the limits to equivalent mass limits. The determination to convert concentration limits to mass limits is within the discretion of the City.
A. The City may establish equivalent mass limits only if the industrial user meets all the following criteria:
1. The industrial user employs or demonstrates that it will employ water conservation methods and technologies that substantially reduce water use during the term of its individual wastewater discharge permit.
2. The industrial user uses control and treatment technologies adequate to achieve compliance with the applicable categorical pretreatment standard, without using dilution as a substitute for treatment.
3. Sufficient information is provided to establish the facility’s actual average daily flow rate for all wastestreams, based on data from a continuous effluent flow monitoring device, as well as the facility’s long-term average production rate. Both the actual average daily flow rate and the long-term average production rate must be representative of current operating conditions.
4. Not have daily flow rates, production levels, or pollutant levels that vary so significantly that equivalent mass limits are not appropriate to control the discharge.
5. Consistent compliance with all applicable categorical pretreatment standards during the period prior to the industrial user’s request for equivalent mass limits.
B. An industrial user subject to equivalent mass limits must:
1. Maintain and effectively operate control and treatment technologies adequate to achieve compliance with the equivalent mass limits;
2. Continue to record the facility’s flow rates through the use of a continuous effluent flow monitoring device;
3. Continue to record the facility’s production rates and notify the City whenever production rates are expected to vary by more than 20 percent from its baseline production rates. Upon notification of a revised production rate, City will reassess the equivalent mass limit and revise the limit as necessary to reflect changed conditions at the facility; and
4. Continue to employ the same or comparable water conservation methods and technologies as those implemented under this section so long as it discharges under an equivalent mass limit.
C. Where the Authority chooses to establish equivalent mass limits, it will:
1. Calculate the equivalent mass limit by multiplying the actual average daily flow rate of the regulated process(es) of the industrial user by the concentration-based daily maximum and monthly average standard for the applicable categorical pretreatment standard and the appropriate unit conversion factor;
2. When notified of a revised production rate, reassess the equivalent mass limit and recalculate the limit as necessary to reflect changed conditions at the facility; and
3. Retain the same equivalent mass limit in subsequent control mechanism terms if the industrial user’s actual average daily flow rate was reduced solely as a result of the implementation of water conservation methods and technologies, and the actual average daily flow rates used in the original calculation of the equivalent mass limit were not based on the use of dilution as a substitute for treatment pursuant to 40 CFR 403.6(d) and this title. The industrial user must also be in compliance with 40 CFR 403.17 (regarding the prohibition of bypass). [Ord. NS-2182, 2012]